Cella PDF User Guide

Cella PDF opens PDF drawing sets the way architects and contractors use them. You can mark them up, measure them and hand them on as ordinary PDFs that Acrobat and other PDF apps read. Nothing leaves your computer unless your office shares its drawings through an Atrium server.

This guide covers Cella PDF on the Mac, Windows and Linux. Every key is given for both: the Mac's first, then Windows and Linux's, as in (⌘O; Ctrl+O); where Windows and Linux differ, each is named (see Keyboard shortcuts). The pictures and videos show the Mac. Every picture is of the same sheet, A-101 First Floor Plan of a small clinic, part-way through a review by four people.

Menus. The commands you use all day sit at the top level of the menus. Occasional ones live in submenus named for the job: File ▸ Export, File ▸ File Tools, Edit ▸ Text Markup, View ▸ Show, View ▸ Layout, View ▸ Compare, Tools ▸ Measure, Tools ▸ Sheet Setup, Markups ▸ Revisions, Redaction, Arrange, Flatten and Changes. This guide writes a command's whole path, as in File ▸ Export ▸ Markups as CSV…. Keys are the same wherever a command sits. If you cannot find a command, open the command palette (⌘K; Ctrl+K) and type a word from its name: it finds everything, submenu items included, and runs it.

#Welcome and licensing

When Cella PDF starts without a document it shows the Welcome window. Open PDF… (⌘O; Ctrl+O) and Open Folder as Set… (⇧⌘O; Ctrl+Shift+O) are on the left, with a place to drop a PDF or a folder. On the right, Recent shows the documents and sets you have had open as cards: a picture of the first sheet, the folder it is in, and the sheet and markup counts from the last time you had it open. Click a card to open it; right-click it for Show in Finder (Show in Explorer, Show in Files) and Remove from Recents. A file that has been moved or deleted is greyed out as "Not found". Join a sync server…, the User Guide (this guide) and the Release Notes are at the bottom.

The Welcome window closes as soon as a document opens. Bring it back with Window ▸ Welcome (⇧⌘1; Ctrl+Shift+1). Untick Show this window at launch to go straight to the Open dialog instead.

Until you have opened it, a Try the sample set card at the top of Recent offers Open the sample drawing (the clinic floor plan used for the pictures in this guide) and Open the sample set (a folder of twelve sheets of the same clinic, A-000 to A-602: cover, notes, code plan, site plan, plans, ceiling plan, elevations, sections, details and schedules). Each puts a copy in Documents/Cella Samples and opens it, and never overwrites a copy you already have. Once you have used it the card goes, and Recent moves up to the top. Help ▸ What’s New lists what every version brought, and Help ▸ Report a Bug… sends us a report (see Getting help).

#Installing

Mac (macOS 12 or later, Apple silicon or Intel). Open the CellaPDF-<version>.dmg you downloaded and drag Cella PDF into Applications. It is signed and notarized, so it opens like any other app; the first time, macOS asks you to confirm.

Windows (Windows 10 or 11, 64-bit, with the Microsoft Edge WebView2 Runtime, which Windows 11 and up-to-date Windows 10 already have). Open CellaPDF-<version>-Setup.msi. It installs Cella PDF for you alone (no administrator password) in your user folder and adds it to the Start menu; later versions install over it by themselves. Uninstall it from Settings ▸ Apps ▸ Installed apps. If you'd rather not use an installer, unzip CellaPDF-<version>-Windows.zip instead and move CellaPDF.exe to a folder you can change, such as Documents (not Program Files), so it can update itself; if the installer fails, use the zip and tell us. The installer and the app are signed by Sorted Solution LLC, so Windows names it as the publisher. A newly signed app can still meet SmartScreen's "Windows protected your PC" for a while: check that it names Sorted Solution LLC, then click More info, then Run anyway. If your IT department allows only approved apps, ask them to allow Sorted Solution LLC's.

Linux (Ubuntu 24.04 or later on x86_64 or arm64, or Arch Linux / Omarchy on x86_64). In the folder where you saved the download:

sudo apt install ./cella_<version>-1_amd64.deb             # Ubuntu; arm64: ./cella_<version>-1_arm64.deb
sudo pacman -U cella-bin-<version>-1-x86_64.pkg.tar.zst     # Arch / Omarchy

iPad. Get Cella PDF from the App Store. The same license key covers it: on the iPad's Home, choose Enter License Key… and paste the key you use on your computer. Cella PDF on the iPad has what differs there.

Cella PDF updates itself on the Mac, Windows and Linux: it checks once a day and asks before installing (see Getting help).

#One product, one key

Cella PDF is one product, the same download for everyone, and a key takes every 1.x update. One key covers one computer (Mac, Windows and Linux) and one iPad. The iPad app comes from the App Store (see Cella PDF on the iPad) and takes the same key.

A 14-day free trial starts by itself the first time you open Cella PDF on a computer, with no sign-up and no payment details, and everything works. The toolbar (status bar on Windows and Linux) counts the days left, and so do About (Free trial · N days left) and the license window. The trial runs once per computer.

When the trial ends without a key, Cella PDF is view-only (About says Trial ended · view only). What stays open to everyone, key or not:

In view-only Cella PDF the markup and measuring tools and the style strip are not on the toolbar, and Undo / Redo and the Tool Palette button are not in the status band. The commands that change a document are greyed out with a tooltip saying a license is needed. If you try one anyway, Cella PDF says: "Your 14-day free trial has ended. Buy Cella PDF or enter a license key to keep marking up." Your drawings and markups stay open and readable, nothing is lost, and markups you haven't saved can still be discarded when you close the window.

#Buying, entering a key and deactivating

The license commands are under Cella PDF ▸ Cella PDF License… on the Mac and Help ▸ Cella PDF License… on Windows and Linux; the Buy Cella PDF… button on the toolbar opens the same window.

• Buy Cella PDF… opens the checkout in your browser; the license key arrives by email.
• Enter License Key…: paste the key (spaces and line breaks from the email don't matter) and click Activate. The computer appears under its own name in your key's list of devices, and About reads Licensed to your name. A key for another product is refused.
• Deactivate This Device… frees this computer's place on the key, for a new computer (on the iPad, it frees the key's one iPad place for another iPad). Do it before you replace or wipe a computer. If the license server can't be reached, the license stays until you try again online.
• Cella PDF checks the license with the store at most once a day. Offline, a licensed Cella PDF keeps working for 30 days after the last successful check. After that it is view-only until Check Again in the license window gets through. A refunded or disabled key switches to view-only at the next check, with a message.

The key is kept in the Keychain on the Mac, encrypted for your Windows account on Windows, and in your desktop's keyring on Linux. Checking it sends Lemon Squeezy, the store that sells Cella PDF, the key and the computer's name, nothing else.

#Windows and Linux

The Windows and Linux versions have the same menus and panels as the Mac and nearly all of its features, with the keys listed under Keyboard shortcuts. Where they differ it is said in the section.

#Getting started

#Opening a sheet or a set

• File ▸ Open… (⌘O; Ctrl+O) opens one or more PDFs. They open as tabs of the front window (see Tabs).
• File ▸ Open Folder as Set… (⇧⌘O; Ctrl+Shift+O) opens a folder of PDFs as a set: every PDF in the folder and one level of subfolders, sorted the way people sort sheet numbers (A-101 before A-1001). The sidebar opens on its Set tab, which lists the files with their markup counts; click one to open it in the same window. More under Folder sets.
• File ▸ Open Recent lists the files you opened lately; the Welcome window shows them as cards.
• You can also drop PDFs and folders on the Welcome window, or PDFs on Cella PDF's Dock icon.
• A picture opens as a new drawing. Choose a JPEG, PNG, HEIC (not on Windows) or TIFF in File ▸ Open…, open it with Cella PDF from the Finder (or Explorer, or your file manager: Open With), drop it on the Dock icon, the Welcome window or an empty window, or pick it from Open Recent. It becomes a new untitled PDF of one sheet, named after the picture (site-photo.jpg opens as site-photo.pdf). The sheet is made as Insert Image Pages makes one: the picture's own size at the resolution the file gives, or at the resolution last chosen in Insert Image Pages (150 dpi at first); JPEGs go in as they are. The picture itself is never changed. Save asks where to put the PDF, starting in the picture's folder; until then closing it asks whether to save only if you marked it up. Choose several pictures and each opens as a drawing of its own. Cella PDF is offered in the pictures' Open With list, never made their default app.
• Make Cella PDF your default app for PDFs with the Finder's Get Info ▸ Open with ▸ Change All…, or on Windows a PDF's Open with ▸ Choose another app with Always ticked. Your PDFs then show Cella PDF's document icon, a sheet with a red PDF label, so a drawing never looks like the app itself. (The Finder shows a preview of the first sheet where it can, and the document icon where it has none. On Linux the file manager keeps your icon theme's PDF icon.)

Cella PDF reopens the documents you had open when you quit (Settings ▸ Reopen documents at launch).

#Opening from the cloud: Dropbox, OneDrive and Google Drive

Cella PDF opens drawings on Dropbox, OneDrive (with SharePoint) and Google Drive and saves back to them, so nothing is downloaded and uploaded by hand.

• Sign in once. Settings ▸ Connected Accounts… (Options on Windows; the iPad's Settings) lists the services with Sign In… for each. Signing in opens your web browser on the service's own sign-in page; Cella PDF never sees your password, and the browser tab says when you can come back. A service can be signed in with more than one account. Sign Out forgets the account on this computer only. If your firm's IT approves apps before staff can use them, they may need to approve Cella PDF once.
• File ▸ Open from Cloud… shows your accounts at the left and their folders at the right: your files, files shared with you, and shared drives (Google Drive) or SharePoint sites you follow (OneDrive). Double-click a PDF to open it. The folder you were in is remembered.
• File ▸ Open Set from Cloud… opens a cloud folder as a set: every PDF in it is downloaded (a progress sheet you can cancel), and File ▸ Set works on it as on any folder. Open the same folder again and only the files that changed are downloaded.
• Save on a drawing from the cloud saves it here first, as always, then uploads it as a new version of the same file; the status band says "Saved to Dropbox 14:02". Each service keeps the earlier versions, so nothing is overwritten. If someone uploaded a newer version while you had it open, Cella PDF asks before putting yours on top. If the upload fails (no network, signed out), your save is safe on this computer and the next Save tries again; the window's subtitle says "not uploaded" until it goes.
• File ▸ Save to Cloud… puts a copy in a folder you choose (with New Folder…), and from then on Save uploads there. Saving to a name that already exists makes a new version of that file.
• Cloud files are kept in a cache folder on this computer, so Open Recent, autosave and crash recovery work on them like any file. Single files not opened for a month are removed; sets stay until you use Clear Cloud Cache… in Connected Accounts. Opening from the cloud works without a licence; saving and uploading need one, like every save.
• On the iPad, Open from Cloud… and Open Set from Cloud… are on the home screen and Save to Cloud… is in the document's share menu, for Dropbox and OneDrive.

#The window

• Toolbar, left to right: Select and Pan; the markup tools; the measuring tools. Undo, Redo, zoom, the Tool Palette and the panel buttons are at the right end of the status band; your saved tools are under Tools ▸ Tool Chest; Open, Save and Print are in the File menu.
• Options row, under the toolbar. It always keeps one height, so the drawing never jumps. While a drawing tool is picked or markups are selected, it shows the colours, fill, line width, opacity and whatever else that tool uses (line ends, cloud, and for text the font, size, bold, italic and alignment).
• The drawing fills the middle. The side panels run the window's full height, so the toolbar, the options row, the sheets strip and the status band are as wide as the drawing.
• Properties, at the right (⌥⌘P; Ctrl+Alt+P), shows the selected markup, or the defaults of the tool you have picked when nothing is selected.
• Markups List, under Properties (⌥⌘M; Ctrl+Alt+M), lists every markup in the document. See The Markups List. Drag the line between Properties and the list to share the column between them. Properties' Style, Position, Organise and People headings fold away with a click, and empty Layer, Space, Label and reply rows stay out of the way until you click "empty" beside the heading. Settings ▸ Panel rows ▸ Compact packs the rows closer, and Settings ▸ Right column puts the Markups List on top.
• Pop the panels out onto a second display, or beside the window on a large one. Each floats in a panel of its own with the pop-out button at the right of the PROPERTIES and MARKUPS captions (two overlapping squares, the same as the Tool Palette button in the status band), with View ▸ Pop Out Properties (⌥⇧⌘P; Ctrl+Shift+Alt+P) and View ▸ Pop Out Markups List (⌥⇧⌘M; Ctrl+Shift+Alt+M), or when you drag a caption off the window. In the panel, the same button (now blue), the same keys, View ▸ Dock … or the panel's close button put it back in the window. Show Properties (⌥⌘P; Ctrl+Alt+P) and Show Markups List (⌥⌘M; Ctrl+Alt+M) still show and hide a popped-out panel. The first time you use Cella PDF, a small tip under the caption points this out; close it with its ×.
• Sheets strip, along the bottom: see below.
• Status band, along the very bottom: Sheet 1 of 1, the sheet's name and scale (click the scale to set it; the text lines up with the first sheet thumbnail above it), the sync state and how many markups are selected, the moon for Invert Drawing and ? for the keyboard shortcuts; then Undo and Redo; zoom out, the zoom percentage (click it for presets), zoom in and Fit Page; the pop-out button for the tool palette and the three panel buttons (Sheets, Markups List, Properties).

The hot colours in the options row (magenta, orange, lime, cyan, violet, yellow, red, blue and ink) are for marking up quickly: click one for the stroke, Option-click or Alt-click for the fill. The Colour… well next to them takes any other colour.

When the window is too narrow for every tool, the ones that don't fit move to a ⋯ menu after the tool groups; their keys still work, and Properties always has the full set of controls. Below 1280 points wide the sidebar floats over the drawing instead of squeezing it. The pin at the top right of the sidebar docks it beside the drawing (or floats it) until you quit, and View ▸ Panels Overlay the Drawing chooses Automatic, Always or Never. Properties and the Markups List always keep their full-height column at the right, so they have all the room the window can give them. That column has no pin and never floats (on Windows and Linux it still floats below 1280 and has a pin).

View ▸ Tool Palette (⌥⌘T; Ctrl+Shift+T), or the pop-out button, floats the tools and the style strip in a small window of their own that you can park beside the drawing; close it to dock them back. On the Mac the toolbar and the options row leave the window while the palette is out, so the drawing reaches up to the title bar. Tool keys still work, and the Tool Chest's tools are in the command palette (⌘K; Ctrl+K, then @).

#The sheets strip and the sidebar

Sheets run as a strip of thumbnails under the drawing (View ▸ Layout ▸ Sheets at Bottom, the default), where a landscape drawing has room to spare. The pill on a thumbnail is its markup count; the sheet on screen is ringed. Click a thumbnail, or click the strip and use ← and → (Home and End for the first and last). When there are more sheets than fit, ‹ and › buttons at the strip's ends scroll it a page at a time (each disappears at its own end). View ▸ Show Sheets (⌥⌘S; Ctrl+Alt+S) hides and shows it. Drag the strip's top edge to make the thumbnails bigger or smaller (double-click it for the usual size), or click the strip and zoom with it (⌘+ and ⌘−; Ctrl++ and Ctrl+−); View ▸ Sheets ▸ Larger Thumbnails and Smaller Thumbnails do the same, and with the sheets at the left they switch the list between small, medium and large thumbnails.

The sidebar at the left opens when you need it: for searching (⌘F; Ctrl+F) and when a folder set opens. Its tabs are Sheets, Set (with a folder set open) and Bookmarks (when the PDF has bookmarks). Close it with the × in its heading. View ▸ Layout ▸ Sheets at Left keeps the sheets in the sidebar instead of the strip, with a filter field above them.

#Zoom and navigation

• Zoom (⌘+ and ⌘−; Ctrl++ and Ctrl+−), a pinch, or the scroll wheel with ⌘ (Mac) or Ctrl (Windows and Linux) held down. View ▸ Fit Page (⌘0; Ctrl+0), Fit Width (⌘1; Ctrl+1), Actual Size (⌘2; Ctrl+2). The fit button beside the zoom in the status band (or a click on the zoom itself) always brings the whole sheet back; Option-click or Alt-click fits the width. Double-click the middle mouse button (the wheel) anywhere on the drawing for the same zoom to extents, as in CAD. Home, or View ▸ Top-Left Corner, puts the sheet's top-left corner back in view at the same zoom. Fit Page and Top-Left Corner can each be given a key in the shortcut settings (search "extents" or "home" there).
• Pan with Space held down while you drag, the middle mouse button, the Pan tool (⇧V; Shift+V), or the scroll wheel and trackpad.
• Sheets: the next and previous sheet with Page Down and Page Up or (⌘↓ and ⌘↑; Ctrl+Down and Ctrl+Up); the first and last with (⌥⌘↑ and ⌥⌘↓; Ctrl+Home and Ctrl+End). Zoom and position stay put when you change sheet.
• View ▸ Go to Sheet… (⌥⌘G; Ctrl+Alt+G, or ⌘G; Ctrl+G when nothing is being searched) takes a sheet number or a sheet name such as A-101.
• With the Select tool, click a sheet reference in the drawing ("12/A-512", "SEE A-301") to go there (see Links).

#The command palette

Help ▸ Command Palette… (⌘K; Ctrl+K) finds any command by typing a few of its letters: "fw" finds Fit Width, "rot" Rotate Right. Each result shows where it lives in the menus and its shortcut; ↑ and ↓ choose, Return or Enter runs it, Esc closes. Start with > to jump to a sheet (with its thumbnail), @ for tools, Tool Chest tools and stamps, and # to find a markup by its subject or comment and select it. The commands you ran lately come first.

#Dark mode and Invert Drawing

Cella PDF follows the system's light or dark appearance; Settings ▸ Appearance chooses System, Light or Dark for Cella PDF alone. In dark mode the panels go dark and the sheet stays paper-white, so colours read as they will print.

For night work, View ▸ Invert Drawing (⌃⌘I; Ctrl+Alt+I), or the moon in the status band, shows the sheets white on near-black. Your markups keep their real colours, a red line in the drawing stays red, and printing, exporting and the thumbnails are unchanged. Cella PDF remembers it.

#Tabs

Documents open as tabs of the front window (Settings ▸ Open documents in tabs turns this off). On the Mac, Window ▸ Show Previous Tab / Show Next Tab (⌥⌘← and ⌥⌘→; Ctrl+Page Up and Ctrl+Page Down) move between tabs; drag a tab out for its own window, or use Window ▸ Move Tab to New Window, and Window ▸ Merge All Windows to gather them again. The + at the end of the tab bar opens a PDF in a new tab. Each tab keeps its own sheet, zoom, panels and selection.

On Windows and Linux a tab strip appears under the toolbar once a window holds two documents. Ctrl+Page Up and Ctrl+Page Down move between tabs, Alt+1 to Alt+9 jump to one, a middle click or the tab's × closes it, and Window ▸ Move Tab to New Window gives a tab its own window.

#Split View

View ▸ Split View (⌘\; Ctrl+\) shows the document twice, side by side (Vertical) or stacked (Horizontal), each pane with its own sheet and zoom: a plan beside its detail. Drag the line between them to resize; double-click it for half and half. View ▸ Split View (⌘\; Ctrl+\) again closes the split; the first pane stays.

• Markups you draw or change in either pane appear in the other straight away; you save as usual (⌘S; Ctrl+S).
• The pane you are working in has a blue outline, and the Markups List, Properties and the sheets strip follow it.
• The link button in the status band (Sync Pan and Zoom) keeps both panes at the same zoom and centre; the two panes button next to it (Sync Sheets) also follows sheet changes.
• Split View ▸ Nudge Second Pane Left / Right / Up / Down moves the second pane's drawing a little, for two issues plotted slightly apart; click the offset in the status band (or Reset Offset) to put it back.
• Open Another File in Second Pane… shows a different PDF there, read-only, for looking at two issues side by side. Show This Document in Second Pane goes back.

Each window or tab has its own split.

#Presentation mode

For a meeting: View ▸ Presentation (⇧⌘↩; F5 on Windows and Linux). The window fills the screen, every panel and bar goes, and the sheet is fitted whole. Under the mouse is a laser pointer, a red dot with a short fading trail that is never a markup and is never saved; drag to pan, use the wheel or a pinch to zoom into a detail, double-click to fit the sheet again.

• → ↓ Page Down, Space or Return go to the next sheet, ← ↑ Page Up or Backspace to the previous, Home and End to the first and last. Each sheet comes up fitted.
• Type a sheet number or name ("A-201", or "12") and press Return to jump to it; the name shows at the bottom as you type, and an exact match goes by itself after a moment.
• The sheet's name and place ("A-101 · 3 / 12") show for a moment after each change.
• Esc ends the presentation (or the ✕ at the top right, shown when the pointer is near the top); the window comes back as it was.

On the iPad, Presentation is in the View menu: one finger or the Pencil is the pointer, two fingers pan and pinch, a tap near the left or right edge turns the sheet, and the ✕ ends it.

#Reading a set

#Sheets and sheet numbers

Cella PDF reads each sheet's number from its title block, so the strip, the sidebar and the status band say A-101 rather than "page 1". A PDF that carries sheet names (page labels) shows those.

• Rename a sheet: double-click its row in the Sheets list, press Return or Enter on it, or right-click ▸ Rename Sheet…; type the name and press Return or Enter (Esc cancels; an empty name goes back to "Sheet N").
• Tools ▸ Sheet Setup ▸ Detect Sheet Numbers… renames every sheet to the number in its title block, replacing the names the file had and your own.
• Tools ▸ Sheet Setup ▸ Sheet Index… reads the drawing list off the cover sheet; see Sheet index.

Saving writes the names into the PDF as page labels, so Acrobat and other PDF apps show the same names.

#Bookmarks

When the PDF has bookmarks, a Bookmarks tab appears in the sidebar. They are nested as the file has them (click a triangle to open or close a group). Click one, or arrow through them, to go to its sheet, zoomed to the place it marks.

You can edit them:

• Sheets ▸ Add Bookmark, or + at the top of the Bookmarks tab, marks the sheet and the view on screen; type its name straight away. ↳ adds it inside the selected bookmark.
• Double-click a bookmark to rename it; Delete (or −) removes it; drag bookmarks to reorder them, or onto another to nest them.
• Markups ▸ Bookmark This Markup (also on a markup's right-click menu) marks a markup, zoomed to it. Sheets ▸ Bookmarks from Sheet Labels… makes one bookmark per sheet, named like the sheet.
• Save writes the bookmarks into the PDF, where Acrobat, Preview and other PDF apps show them too. Undo (⌘Z; Ctrl+Z) undoes bookmark changes one at a time, with your markup edits. Bookmarks follow their sheets when you move or insert sheets.

#Search

Edit ▸ Find… (⌘F; Ctrl+F) puts the cursor in the sidebar's search field. Type and press Return or Enter to search the drawings' text and the markups (subjects, comments, replies, custom columns and stamp text). The results replace the sheet list, grouped by sheet with their counts and the match in bold; the field shows "2 of 16".

• ↑ and ↓ move through the hits; Return or Enter jumps to one (again: to the next).
• Edit ▸ Find Next (⌘G; Ctrl+G or F3) and Find Previous (⇧⌘G; Ctrl+Shift+G or Shift+F3) step through them from anywhere. Esc clears the search.
• The toggles under the field: Aa Match Case; W Whole Word ("22" finds DETAIL 22/M-152 but not M-222); .* Regular Expression (A-5\d\d, RFI\s*12; a pattern with a mistake says so); and the speech bubble, which includes the markups.
• With a folder set open, Whole Set searches every file (the same choice as the Markups List's This File / Whole Set). Results are grouped by file; choosing a hit in another file opens it there. Cella PDF keeps what it read of each file in the .cella folder beside the files, so a second search of a big set takes a moment instead of reading every PDF again.
• Replace…, under the field, changes the matching text in this file's markups (subjects, comments and replies: "ASI 4" to "ASI 7") after telling you how many it will change. One Undo puts it all back.

Visual Search finds a symbol by how it looks, not by its text. Choose Visual above the toggles (Markups searches only the markups' text), click Pick Symbol… and drag a box around one door swing, receptacle or fixture tag on the sheet. Cella PDF lists every other place it is drawn, grouped by sheet like text hits, and outlines them on the sheet. All Sheets looks on every sheet of the document; Rotations also finds it turned 90°, 180° or 270°; Size ±10 % finds it a little smaller or larger; and the Match threshold slider (60–95 %) says how alike a place must be. Place Counts then puts a Count markup on every symbol found, with the Count tool's symbol, ready for the take-off. Mark for Redaction covers each one with a redaction mark. One Undo takes either back.

Scanned sheets are pictures with no text, so there is nothing to find on them until you choose Document ▸ Recognize Text (OCR)…. Pick the sheets without text, this sheet or all of them, and Cella PDF reads the words on your computer (nothing is sent anywhere). Search, Find Next, Whole Set, selecting and copying text, highlighting it, Mark Search Results for Redaction and Detect Sheet Numbers then work on those sheets. The words are kept in the .cella folder beside the file and the PDF is left as it was, unless you tick Also write an invisible text layer into the file so other apps can search it too. Settings ▸ Recognize text on scanned sheets automatically reads a scanned title block for its sheet number when a set opens. The Mac reads with its own text recognition and Windows with Windows' own (it uses the OCR languages installed with Windows). On Linux, install Tesseract (for example sudo apt install tesseract-ocr); Cella PDF doesn't bundle it.

To check what was read, choose View ▸ Show ▸ Recognized Text. Every word Cella PDF found gets a thin box on the sheet, with the word in a small label when you point at it. Words the Mac's recognition was unsure of are boxed in amber (Windows doesn't say how sure it is), and words you corrected in green. Double-click or right-click a word to fix it: type the right word and press Return or Enter, press Esc to leave it, or press Delete to remove a word that isn't one (a smudge read as text). Search and selection use your correction at once, Undo takes it back, and it is kept beside the file with the rest of the words. When you recognize the text again, Keep my corrections (on by default) keeps each corrected word that is found again in the same place. If you wrote the invisible text layer into the file, the file keeps the earlier words until you run Recognize Text again with that box ticked.

#Selecting and copying the drawing's text

With the Select tool, drag across the drawing's own text (the pointer becomes an I-beam over it) to select it, as in Preview. The selection follows reading order across lines, and down a notes column rather than across the plan beside it. Double-click selects a word (a sheet reference such as 12/A-512 counts as one), triple-click a line, Shift-click extends. Copy (⌘C; Ctrl+C) copies it; Esc or a click elsewhere clears it.

Right-click the selection (or use the Edit menu) to Search for it, or to Highlight, Underline or Strikeout it, or Mark Text for Redaction. The rule that lets one Select tool do both jobs: a drag that starts on a markup moves the markup, one that starts on text selects text, and one that starts on empty paper draws a marquee that selects markups.

#Layers

View ▸ Layers lists the PDF's own layers (what the CAD export put on layers) and the layers markups use (trace sheets among them, see Trace Paper); untick one to hide it. View ▸ Show Markups hides every markup at once, to see the bare drawing.

#Links

Links take whoever clicks them somewhere: another sheet, a detail at a zoom, a web page or another file. With the Select tool a click follows a link (also when the trial has ended); the status band says where a link goes while the pointer is over it. View ▸ Show ▸ Links outlines every link on the sheet.

Tools ▸ Sheet Setup ▸ Link Sheet References… turns every sheet number in the drawings' text into a link to that sheet, across the files of a set. Running it again replaces the links it made before, but not ones you have edited.

Making your own links:

• Tools ▸ Link (K): drag a rectangle over what should be clickable, then choose what it does: - Go to a sheet: fitting the whole sheet, keeping the zoom, or showing a region (Choose Region… takes you to that sheet to drag the region, then back). - Go to a snapshot view: Choose View… takes you to the sheet; pan and zoom to the view and click Use This View (or press Return or Enter). - Open a web address, or Open a file (another PDF, and the page to open it at). - A border (none, underline or box) and its colour.
• Markups ▸ Add Link to Markup… (or the markup's right-click menu) puts a link on a markup, and it moves with the markup. ⌘-click (Mac) or Ctrl-click (Windows and Linux) the markup to follow it; a plain click still selects it, and a ⌘-drag or Ctrl-drag moves it free of snapping without following the link.
• To change or remove a link, pick it with the Link tool (or right-click it). Properties shows where it goes, its border and colour, with Edit Link…, Follow and Remove. Drag it with the Link tool to move it; Delete removes it.

Links are standard PDF links: Acrobat, Preview and other PDF apps follow them. Rotating, moving, inserting and deleting sheets keeps every link on its sheet and pointing at the right one.

#Spaces

Spaces are named areas of a sheet (rooms, zones, units). Every markup drawn or moved inside a space takes its name in the Space column of the Markups List, so you can count and total by room.

• Tools ▸ Space (⇧S; Shift+S): click the corners of the room, double-click (or press Return or Enter) to close it, and name it. The tool stays on for the next room.
• While the Space tool is on, Properties lists the sheet's spaces: type over a name to rename it; the bin deletes it; Copy to All Sheets (also Tools ▸ Sheet Setup ▸ Copy Spaces to All Sheets) puts the same spaces on every other sheet, for floors that share a plan.
• Tools ▸ Sheet Setup ▸ Create Spaces from Rooms… finds the rooms for you, the way Dynamic Fill does. Every area of at least 20 sq ft that the walls close (doors narrower than the Fill gap count as closed) becomes a proposed space, named after the text inside it ("OFFICE" with "201" under it becomes OFFICE 201; a room without text is Room 1, Room 2…). Choose This Sheet or All Sheets, untick what you don't want (a title block's boxes, say), rename any, and click Create. A room that already has a space is listed as "already a Space" and left unticked. Markups inside take the names at once, and one Edit ▸ Undo takes all the new spaces away.
• View ▸ Show ▸ Spaces shows them as faint tinted areas with their names. Other PDF viewers never show or print them.
• A markup takes the space its middle is in (the smallest one, where spaces overlap). To choose one yourself, pick it or type it in Properties ▸ Space; the markup then keeps that name wherever it moves. Clear the field to let its position decide again.
• Markups List ⋯ ▸ By Space groups the list (and the CSV) by space, with totals; Markups ▸ Insert Legend… can group by space too.

#Compare

Cella PDF has two ways to see what changed between two issues of a sheet.

View ▸ Compare ▸ Compare With… (⇧⌘K; Ctrl+Shift+K) overlays another issue on the sheet on screen: the linework both share dark, this issue red, the other blue. Step through the sheets with View ▸ Compare: Previous Sheet / Compare: Next Sheet, and Stop Comparing when you are done. The status band says what you are comparing with. When other PDFs are open, in tabs or other windows, Compare With… lists them first (Compare with:); Another File… asks for a file instead.

View ▸ Compare ▸ Compare Documents… finds what changed and clouds it. Pick the other issue, then choose:

• Compare with: when other PDFs are open, in tabs or other windows, the first choice lists them: pick the other issue there, with no file to find. Another File… asks for a file once you click Choose File…. An open document is compared as it was last saved. With no other PDF open, Compare Documents asks for the file first.
• Sheets: This Sheet, or All Matching Sheets (paired by sheet number when both are sets, else page by page).
• This document is: The Newer Issue or The Older Issue (whether a change reads "added" or "removed").
• Sensitivity (Low, Medium, High), Smallest change (on Windows "Ignore changes under"; 1, 3, 6 or 12 pt) and the Cloud colour; untick Cloud the changes just to count them.

Cella PDF lines the sheets up (small plot offsets are absorbed), draws a cloud round each change on the layer Compare, commented "added", "removed" or "changed", and filters the Markups List to them. Edit ▸ Undo takes the whole run back; Markups ▸ Changes ▸ Remove Compare Clouds clears them later. Use Compare With… to look closer at one. File ▸ Set ▸ Compare Set with Folder… does the same for every file of a set; see Folder sets.

File ▸ Set ▸ Compare Sets… compares a whole issue with the previous one. Open the new issue as a folder set (or open it as one multi-sheet PDF) and choose the previous issue's folder (or PDF). Cella PDF pairs the sheets by sheet number, whatever the files are called: the number in the title block or the page label, else the file name. Each pair is compared as above (Resolution and Plot offset trade speed for finer changes and larger re-plot shifts). The changes are clouded on layer Compare, and each sheet's count is reported, with the sheets new in this issue and the ones removed. Tick Save a Compare Report for a PDF listing every pair with its counts and a picture of each clouded region. The other files of the set are saved with their clouds; the open file's clouds are one Edit ▸ Undo step. Cancel while it compares leaves every file exactly as it was.

File ▸ Set ▸ Resubmittal Report… writes the same comparison the way a city's plan reviewer asks for it: a resubmittal response. Open the new submission (a folder set, or one multi-sheet PDF), choose the previous submission, and fill in the cover: Project, Submission (say "Resubmittal 2 · Permit B-2026-0412"), the Date and who it is Prepared by. Paste the reviewer's numbered comments into Reviewer comments, one per line as the reviewer numbered them (1., 2), #3); a line starting with > is your response to the comment above. Name the sheet in a comment ("Provide guardrail detail on A-501") and the report links the comment to that sheet's changes. If the reviewer marked up your set instead, Read Comments from PDF… reads every markup with words as a comment, on the sheet it sits on. Then Save Report…. The PDF has a cover with a summary, Changes by sheet (every changed sheet with its revision from the schedule, "Rev 2 (was 1)", its counts, and a BEFORE / AFTER picture of each clouded region; then the unchanged, new and removed sheets), and Responses to review comments (number, sheet, comment, response). A comment without a response gets one drafted from the changes ("Revised; see the 3 clouded changes on A-102.") so you can edit rather than write; the result tells you how many were drafted. Tick Also save the responses as an Excel workbook for the same table as an .xlsx beside the report. Nothing in the set is clouded or saved. On the iPad the Set menu's Resubmittal Report… asks for the project and submission and, if you like, the reviewer's PDF, and hands the report to the share sheet.

#Overlay pages

View ▸ Compare ▸ Overlay Pages… draws two to four sheets on top of each other, each in its own colour. You can see at a glance what moved between two issues, or where the structure clashes with the architecture. Ink that only one sheet has keeps that sheet's colour (blue for the first, red for the second, then green and magenta); where the sheets agree, the colours multiply to black.

1. Choose the sheets. Each row is a sheet of this document or, with Choose File…, of another PDF; click the colour well to change its colour. Add Sheet adds a third and fourth; − removes one. To overlay two sheets of this document you can also select them in the Sheets list and right-click ▸ Overlay These Sheets.
2. Choose the alignment. Automatic finds the offset between the sheets (a plot shifted by up to about two thirds of an inch). None lays the top-left corners together. Pick Points… shows the sheets side by side: click the same two or three points on each, in the same order (grid intersections or column corners far apart work best). Two points move, turn and scale the sheets to match; three also correct a skew.
3. Choose the output. Insert as New Sheet adds the overlay right after the first sheet, named "Overlay of A-101 and A-101 (rev 2)" (Edit ▸ Undo takes it out again); Save as PDF… writes it as a one-page PDF and leaves the document as it was.
4. Check the preview and click Overlay.

The overlay is a picture of the sheets (150 dpi) without their markups: it is for looking, not measuring. Compare Documents… is the tool that finds and clouds the changes.

#Place a PDF

Markups ▸ Place PDF… lays a page of another PDF over the sheet as a drawing you can move, scale and turn, the way you place a PDF drawing over a plan in a CAD program: the consultant's structural plan over your floor plan, last issue's layout over this one, a manufacturer's detail beside yours. Unlike Overlay Pages it adds no sheet and makes no picture; the page stays sharp lines at any zoom, and it is a markup like any other. Right-click an empty part of the sheet ▸ Place PDF Here… to put it where you clicked (on the iPad, touch and hold ▸ Place PDF Here…).

1. Choose the PDF. For a file of several pages, choose the page.
2. Choose the scale. It goes in at its true size: a 36 × 24 in sheet is 36 × 24 in on yours. When the page and your sheet both have a scale (one set with Set Scale…, or from the file), you can Match the sheet's scale instead: a 1/8" = 1'-0" plan placed on a 1/4" = 1'-0" sheet goes in at 200 %, so a wall is as long on both.
3. It lands centred in view, half see-through and selected. Drag it to line it up (snapping works as for any markup); drag a corner to scale it, which keeps its proportions.

Properties ▸ Placed PDF (Mac and iPad) has the rest:

• Scale: type a percentage of its true size (100 % = as drawn); it scales about its centre.
• Turn Left / Turn Right: a quarter turn about its centre.
• Tint: one colour for all its linework, paper staying white (blue, red, green or magenta, as Overlay Pages' colours), so it reads as an overlay against your black drawing.
• Behind markups: draw it under the sheet's other markups (it also goes to the back).
• Visible: hide it without deleting it. A hidden placed PDF is not drawn or printed, and a click goes through it; select it in the Markups List to show it again.

Opacity (50 % to start), Layer and Locked are the rows every markup has: a locked one doesn't move, scale or turn. The placed drawing is laid over the sheet so the paper drops out (the two multiply, as a light table would show them): your sheet's lines read through it at any opacity. Edit ▸ Undo takes back placing, moving, scaling and turning it. The Markups List shows it as "Placed PDF", with the file's name as its comment.

When you save, the page goes into your PDF as vector drawing (in a stamp, so other PDF viewers show it where you left it) and opens again as a placed PDF you can still move. Markups ▸ Flatten burns it into the sheet like other markups (a hidden one is left as it is). The placed page's own markups are not brought along.

#Trace Paper

Trace paper is a see-through sheet laid over the drawing, as you would roll trace over a print to sketch a scheme without touching the plan underneath. View ▸ Trace Paper ▸ Add Trace Paper lays a sheet over the whole page (on the iPad, the View menu's Trace Paper ▸ Add Trace Paper, or touch and hold an empty part of the drawing). View ▸ Trace Paper ▸ Trace Paper Panel opens the Trace Paper panel (on the iPad, the sidebar's Trace Paper pane). Everything stays vector: lines on the trace are sharp at any zoom and in print.

• Drawing on it. The new sheet is the active one, marked in the panel: everything you draw goes on it (with a pen or Apple Pencil too) until you pick another sheet, or Drawing to mark up the drawing itself again.
• Several sheets. A page can have as many sheets as you like, stacked: each one is drawn over the sheets under it, with its own markups on top of its paper, and the drawing's own markups stay under them all. Move a sheet up or down the stack from the panel. Double-click a name (on the iPad, swipe or touch and hold) to rename it; "Scheme A", "Option 2".
• Look. White or Yellow trace, its opacity, and Dim the drawing: on, the paper fades the drawing under it as real trace does; off, the paper only tints it, so the drawing stays at full strength (with white trace you then see only your sketch).
• Show and hide. The eye beside a sheet hides it with everything on it. View ▸ Layers lists each sheet too. View ▸ Trace Paper ▸ Hide All Trace hides every sheet in the document at once, to see the clean drawing; Show All Trace brings them back. Nothing is drawn onto a hidden sheet.
• Move / Turn. Press Move / Turn, then drag anywhere to slide the sheet over the drawing; its markups go with it. Drag the round handle above it to turn it (hold Shift for steps of 15°); the arrow keys nudge it. Press Return or Escape, or Move / Turn again, when it is where you want it. Reset puts it back where it was laid. Each move and turn is one Undo. Shapes drawn as boxes (rectangles, ellipses, text boxes, stamps) turn round with the sheet but stay square to the page; lines, polygons, clouds and pen strokes turn exactly.
• Clip. A sheet need not cover the whole page: Clip ▸ Clip to Rectangle (drag a box) or Clip to Polygon (click the corners; double-click, Return or a click on the first corner closes it) cuts the paper to that region; Clip to Selection uses a selected rectangle, polygon or cloud; Whole Page lays it over the page again. View ▸ Trace Paper ▸ Clip to Region… clips the active sheet to a box you drag. Markups on the sheet are not cut.
• Removing a sheet takes its markups with it, or Keep Markups puts them back on the drawing.

Saving and other viewers. Each sheet is saved as a PDF layer (an optional content group) of its own name, with the paper and the sheet's markups on it, so other PDF viewers show a layer you can switch on and off. A sheet you leave hidden is saved hidden.

Flatten, export and print. The panel's In exports says which sheets Flatten, Export Flattened Copy, the Summary PDF, Print and Export to DXF take: Visible sheets (the start), All sheets, or None. View ▸ Trace Paper ▸ Include Trace in Exports is ticked unless it is None; choosing it switches between Visible sheets and None. A hidden sheet left out of a flatten stays a sheet you can still edit. In a DXF each sheet is a layer with its paper's edge and its markups.

#Marking up

Marking up needs a key or the trial. Pick a tool from the toolbar, the Tools menu or the tool palette, or press its key while the drawing has the keyboard. A tool goes back to Select after one markup; Shift-click a tool (or press its key twice) to keep it. Esc goes back to Select, or cancels the markup you are drawing.

#The tools

Edit Text (⇧T; Shift+T) changes the drawing's own text, not a markup: click a line of it and a field opens there with its words. Type, and press Return or Enter (Esc leaves it as it was). The sheet's text is rewritten where it is, in the same font, size, colour and place; letters you keep don't move, and longer text runs on to the right. Click a line of a paragraph (a note of several lines in one font and size, lined up on the left and evenly spaced) and the whole paragraph opens in one box: when you press Return or Enter it is broken into lines again at its own width and line spacing, with lines added below or taken away as the text needs. The rest of the sheet doesn't move, so a paragraph that grows runs down over whatever is under it; check it, and Undo if it collides. Text inside a block is edited too when the block is placed once. A block placed several times (a detail tag, a door number used everywhere) is refused with how many times it is placed, since changing it would change every copy. CAD files often embed only the letters they use. If you type a letter the drawing's font doesn't have (an "É" in a sheet that never had one), Cella PDF writes the line with Liberation Sans (or the matching serif or monospace face, bold or italic like the original) at the same size, colour and place. It says so in the status band ("Written with Liberation Sans: the drawing's font has no “É”"). It is one step of Undo. Cella PDF says so plainly and changes nothing when it can't do it faithfully, as with a character neither font has, text drawn in a Type 3 font or used as a clipping outline, and text in a block inside another block. It is not carried by sync: a synced document refuses it, as it does cropping and resizing.

The measuring tools are under Measuring. Later, double-click a segment of a polyline, polygon or cloud to add a vertex, and Option-click or Alt-click a vertex to remove it.

Points you place, markups you move and handles you drag stick to the drawing, its text and pictures, and your other markups: see Snapping.

#Drawing with a pen

A pen display or graphics tablet (a Huion Kamvas, an XP-Pen, a Wacom, a Surface pen, Apple Pencil) draws with the Pen tool (P). With the Pen chosen, the options row under the toolbar has:

• Pressure. The line gets wider as you press harder. It is on unless you turn it off; a mouse always draws an even line. Curve sets how the pen feels: Light widens the line sooner, for a light hand; Firm needs a firmer press; Normal is the pen as it is. The curve is applied as you draw, so a stroke looks the same on any computer.
• Steadying (Off, Light, Normal, Strong) smooths the line against a shaky hand. It belongs to the pen's look, like its width.
• Straighten. Hold the pen still for a moment at the end of a stroke, before you lift it, and the stroke becomes a straight line from where it began. Keep moving after it straightens to move the line's end. It is off unless you turn it on.
• Ortho (F8 on every computer, or Tools ▸ Ortho). Lines keep to 0°, 45° and 90° on the sheet, as when you hold Shift, without holding it: Line, Arrow, Polyline, Polygon, Cloud and the measuring tools. With the Pen, a stroke becomes one straight line from where it started, at the nearest of those angles. Press F8 again to turn it off. The status band says Ortho while it is on.
• Ortho angle, for skewed plans. When a wing or a grid sits at an angle, give the sheet its own Ortho angle and lines keep to that wall and its square instead (Shift too). Type it with Tools ▸ Ortho Angle ▸ Set Angle… or in the angle box beside Ortho, or choose Tools ▸ Ortho Angle ▸ Pick from Drawing (the eyedropper beside the box) and click two points along a wall or grid line; snapping helps you land on the line, and Esc cancels. The angle is measured as the sheet reads on screen and is kept with that sheet in the document, so each sheet can have its own and it is still there when you open the file again; Undo takes a change back. Tools ▸ Ortho Angle ▸ Reset to 0° puts it back to 0°. The Step items in the same submenu (or the step box) chooses how far apart the angles are: 45° (the usual), 15°, 30° or 90°. While Ortho is on the status band shows the angle, for example Ortho 32.5°. On iPad, the angle button beside Ortho in the options bar holds the same choices.
• Favourites. Up to nine saved pens, each a colour swatch. Set the pen up (colour, width, opacity, pressure, curve, steadying) and click + to save it; click a swatch to draw with it. While the Pen is chosen, the keys 1 to 9 pick favourites 1 to 9. Right-click a swatch (on iPad, touch and hold) to rename or delete it. They are kept in the Tool Chest as the set "Pen Favourites", so they go with an exported Tool Chest.

The pen's buttons. Where the pen reports it, its eraser end erases pen strokes whatever tool is chosen. The barrel button is a right click (the context menu), as everywhere else on the computer.

Windows: turn on Windows Ink. Pen pressure on Windows comes through Windows Ink. In the Huion or XP-Pen driver's pen settings, turn on Windows Ink. Without it the pen works as a mouse and draws an even line. On a Mac, Cella PDF reads the tablet's pressure itself; keep the driver installed. On Linux, pressure comes from the tablet driver your desktop uses (libinput or the Wacom driver); if a stroke stays an even width, check the tablet is set up as a pen in your desktop's settings.

#Snapping

Cella PDF snaps what you draw to what is already on the sheet. As the pointer comes within reach of something, a marker shows what it caught, and the point you click, the corner you drag or the markup you move lands exactly there.

So a callout's leader can land on a word, a rectangle can hug a note block, and a cloud can line up with the one beside it.

• Snap to Drawing (Tools menu, ⌥⌘N; Ctrl+Alt+N) turns snapping on and off.
• The Snap pull-down in the status band, the target with a ▾ beside the zoom, has the same switch and a checkbox for each kind: Linework, Text, Images, Markups, Guides and Spacing. Tools ▸ Snap To has the checkboxes too. Cella PDF remembers your choice. The target is struck through while snapping is off.
• Hold ⌘ (Mac) or Ctrl (Windows and Linux) to draw free while you hold it: drawing, moving and resizing ignore everything. Shift still keeps lines at 45° steps and boxes square, and Option or Alt still puts an arc point or a cut-out.
• Moving a markup snaps by its corners, centre and points, and lines it up with others on a guide. Dragging a handle snaps that corner or point. A markup never snaps to itself.
• Spacing: when a markup you move or a point you draw is about as far from the markup beside it as that one is from the next in the row (or column), or about midway between two, it snaps to the even spacing. Both gaps show with their distance, in the sheet's units when it has a scale.
• Highlight, underline and strikeout follow the words instead, and the pen draws free.

#Properties and the style strip

Select a markup and Properties shows everything about it: Subject, Status, Comments, your office's custom columns, stroke and fill colour, line width, opacity, dash and line endings, font size (and for text boxes and callouts Align, Vertical, Margin (pt) and Spacing), Position, Layer, Space, Label, Locked, the author and dates, the replies and the history. With several markups selected, a change applies to them all.

The style strip in the options row under the toolbar is the quick way to change colour, fill, width and opacity. Changing a style with nothing selected makes it the tool's default from then on, as does Markups ▸ Set as Default for Tool with a markup selected.

Right-click a markup for Delete, Duplicate, the order, the status, Lock, Add Link to Markup…, Bookmark This Markup and Add to Tool Chest….

The basic editing keys: Delete removes; the arrow keys nudge (Shift 10 points, Option or Alt a tenth); Duplicate (⌘D; Ctrl+D) duplicates; Undo (⌘Z; Ctrl+Z) and Redo (⇧⌘Z; Ctrl+Y on Windows, Ctrl+Shift+Z on Linux) step back and forward (Undo reaches back up to 300 steps; older ones are dropped); Select All (⌘A; Ctrl+A) selects every markup on the sheet. Copy (⌘C; Ctrl+C) and Paste (⌘V; Ctrl+V) copy and paste markups between sheets and windows.

#Statuses, replies and comments

Every markup can carry a status: None, Accepted, Rejected, Cancelled or Completed (a firm profile can add its own, such as For Review). Set it in Properties, with Markups ▸ Set Status ▸, or from the right-click menu. Acrobat and other PDF apps read the same review states.

Replies are written in Properties: type in the field under the replies and click Reply. They are threaded the way Acrobat and other PDF apps show them, with the author and date of each.

#Text boxes and callouts

Select a text box or callout and Properties shows Align (left, centre, right), Vertical (top, middle or bottom of the box), Margin (pt) (the space between the box's edge and its text) and Spacing (single, 1.15, the default 1.2, 1.5 or double). Set them with nothing selected and the Text Box or Callout tool uses them from then on. They are saved in the PDF's own text style, so a box made in another markup app opens with its margin, alignment and spacing. That app shows Cella PDF's boxes the same way.

A text box's outline is optional: untick Border (in Properties under Width, and in the options row) and the box is drawn without it, on screen and in the saved PDF; its fill and text stay. While it has no border its Width is greyed. Tick Border again and the outline comes back in the box's colour. Untick it with nothing selected and the Text Box tool makes borderless boxes from then on; a Tool Chest tool made from a borderless box keeps it. Other PDF apps show no border either, and a text box from another app that has none opens with Border off.

A callout always has its border: other PDF apps draw a callout's box with its leader line, so a callout without one would not look the same everywhere. For text without a box, use a text box and an arrow.

Autosize Text Box fits a box to its text. Select one or more text boxes or callouts and choose Markups ▸ Autosize Text Box (⌥⌘Z; Alt+Z on Windows and Linux), or right-click one and choose it there. The box keeps its width and grows or shrinks in height until every line shows, with its top edge where it was (a box aligned to the middle or bottom keeps that instead). A one-line note in a box wider than it needs is pulled in to fit the words. A word longer than the box is never broken: the box widens to it. Text on a turned sheet grows down the sheet as you read it, and a callout's leader follows its box so it still points where it did. It is one step of Undo. On iPad, long-press the box and choose Autosize Text Box, or press ⌥⌘Z on a keyboard.

Boxes an AI assistant adds are sized to their text the same way, as are sequence labels: a box the assistant gives a size keeps its width and only grows taller when the text needs more room.

Moving notes without re-aiming them. Drag a callout's box and only the box moves: the arrow's tip stays on what it points at, and the leader re-attaches to the side of the box nearest the tip (left or right, or the top or bottom when the tip is under or over the box), swapping sides as you drag the box past the tip. So you can tidy a sheet's notes into a column without touching their arrows. Hold Option (Mac) or Alt (Windows, Linux) while you drag to move the whole callout, arrow and all. The arrow keys move a selected callout's box the same way. When several markups are selected (or the callout is in a group), they move together, callouts included, arrows and all.

To re-aim a callout, select it and drag the round handle at the tip; it snaps to the drawing's corners and lines when snapping is on. The smaller round handle is the knee, where the leader bends.

More than one leader. One note can point at several things: right-click the callout (on the iPad, touch and hold) and choose Add Leader. If you right-click the paper beside a selected callout, the new arrow points there; otherwise it starts just below the first one, ready to drag into place. The Add Leader button in the Callout options row does the same for the selected callout. To remove one, right-click on that leader and choose Delete Leader (a callout always keeps at least one). Each leader moves with the box like the first. Other PDF apps show every leader; they keep the first as the callout's own and draw the rest as part of the callout's picture.

#Arranging and editing markups

The Markups menu has what you need to tidy a sheet. Directions are always as you see the sheet, even on a turned one, and locked markups stay where they are. Each of these is one step of Undo.

• Align ▸ Left, Centre, Right, Top, Middle or Bottom lines two or more markups up with that edge (or centre) of the selection as a whole. Distribute ▸ Horizontally or Vertically spaces three or more evenly. Match ▸ Width, Height or Size makes the others the size of the markup you selected last.
• Group (⌃⌘G; Ctrl+J) makes the selection one group: it selects, moves, copies and deletes as one, and other markup apps read it as a group. Ungroup (⌃⇧⌘G; Ctrl+Shift+J) takes it apart.
• Copy Style (⌥⌘C; Ctrl+Alt+C) and Paste Style (⌥⌘V; Ctrl+Alt+V) copy one markup's colours, line, fill, opacity, dashes, endings, cloud border and text settings onto the selection, in this window or another.
• Rotate ▸ 90° Clockwise, 90° Counter-clockwise or 180°, and Flip Horizontal / Vertical (text isn't mirrored).
• Offset… (⌥⌘O; Ctrl+Alt+O) copies the selected lines, polylines, lengths, shapes and areas a set distance away: a line or polyline parallel to itself, a shape or area grown outward or shrunk inward. The copy follows the pointer: move to the side you want and either type a distance (6", 12'-6", 150 mm, as the sheet's scale reads it) and click or press Return, or click through a point to set the distance there (it snaps to the drawing). Esc cancels. The distance you typed last comes back next time, so a run of offsets is a click each. Corners stay sharp, curves stay curves, and an area's cut-outs move the other way. On iPad, long-press the markup, choose Offset…, enter the distance and tap the side.
• Bring to Front (⇧⌘]; no key on Windows and Linux), Bring Forward (⌘]; Ctrl+]), Send Backward (⌘[; Ctrl+[) and Send to Back (⇧⌘[; no key on Windows and Linux) change the order; it is saved in the PDF.
• Lock / Unlock (⇧⌘L; no key on Windows and Linux) stops a markup being moved or changed by accident.
• Move to Layer… puts the selection on a markup layer (type a new name to make one).
• Edit ▸ Select All on Sheet of This Type selects every markup of the selected one's kind on the sheet; Select Similar those with the same subject and colour.
• Properties ▸ Position shows the selection's X, Y (from the sheet's top-left corner), W and H in points, and beneath them the same in the sheet's scale. Type a value and press Return or Enter to move or resize exactly: points, or a length such as 12'-6" or 3.5 m in the sheet's scale.
• Hold Shift while dragging a corner handle to keep a box's proportions.

#Revision clouds and tags

Every change in a revision gets a cloud and a revision delta: a small triangle with the revision number. Tools ▸ Revision Cloud (⇧C; Shift+C), or Markups ▸ Revisions ▸ Revision Cloud, draws both at once. Click round the change as with the Cloud tool, then click the first point again (or double-click, or press Return or Enter) to finish. The cloud gets a triangle at its top-right corner numbered with the current revision. The cloud and its triangle move, copy and delete together. The first revision cloud in a document starts revision 1, dated today.

Select a revision cloud to see its Revision in Properties: pick another revision from the list, or New Revision… to add one. Description says what changed (it is also the comment); Tag turns the triangle into a circle or a hexagon if your office draws them that way.

Markups ▸ Revisions ▸ Revision Schedule… lists the document's revisions with their dates, descriptions and how many clouds each has. Add… starts a new revision (it becomes the current one), Set Current (or a double-click) picks another. You can edit a number, date or description in place; renumbering a revision renumbers its triangles too. Remove takes a revision out of the schedule but leaves its triangles alone.

Markups ▸ Revisions ▸ Insert Revision Schedule (or Insert Table in that window) puts the schedule on the sheet as a table (No., Date, Description, Clouds) at the bottom right, where the title block's revision block usually is. It keeps itself up to date as revisions are added.

A set that arrives with its revisions already drawn in the title blocks doesn't need typing in: Document ▸ Detect Revisions… reads the revision table in every sheet's title block (the rows of number, description and date, the number often in a triangle; dates such as 10/15/26, 2026-10-15, 15 Oct 2026 or OCT 15 2026) and proposes the schedule. Untick a row to leave it out, or double-click a number, description or date to correct it; a number that two sheets describe differently is marked in red with what the other sheet says. Apply fills the Revision Schedule and marks each sheet with its latest revision and that revision's date, which the Sheet Index, the transmittal and Rename Files' {rev} use. No clouds are drawn, and Edit ▸ Undo takes it all back. A scanned sheet is read from its recognized text, so run Recognize Text (OCR) on it first. The Sheet Index window's Read Revisions… button opens the same window. With a folder set open (File ▸ Set) it reads every sheet of every file, naming each sheet's file beside it, and Apply writes each file's own revisions into it and saves it (a digitally signed file is left as it is and named).

In the Markups List, ⋯ ▸ By Revision groups the clouds and their triangles by revision. In the PDF the triangles are ordinary comments that Acrobat, Preview and other PDF apps show as drawn; revision triangles from other apps whose subject reads "Revision 3" or "Rev 3" group under that revision.

#Stamps

Tools ▸ Stamps ▸ lists the built-in stamps (APPROVED, REVIEWED, NOT FOR CONSTRUCTION and the rest) and, under My Stamps, your own. Pick one and click on the sheet to drop it; drag to size it. Some fill in the date, the time and your name as they are placed.

Tools ▸ Stamps ▸ Create Stamp… makes your own: a Title (CHECKED), an optional Subtitle ("by {author} on {date}"), the Fields to fill in each time it is placed (Date, Time, Author, File, Sheet, Page), the Shape (Rectangle, Rounded, Oval or None) and the Colour. It joins Tools ▸ Stamps and the Tool Chest.

To use your firm's own approval stamp or logo, switch Stamp to Picture, give it a Name and Choose Picture… (a PNG or JPEG). It keeps its colours. Make white paper transparent (on at first) clears the white around a scanned stamp so the drawing shows through. If a pale background is left, move Lighter than to the left. Turn it off for a picture that already has a transparent background, or to keep a white box behind the stamp. Very large pictures are scaled to 2048 pixels across, which is still sharp at any size you place them. Choose Picture… opens in the folder you last chose a stamp or signature picture from. A picture stamp drops at its own shape: click to place it about as wide as a text stamp, or drag to size it (it keeps its proportions). Like your other stamps it is listed under My Stamps, travels with exported profiles and Tool Chest files, and works with Apply Stamp to Every Sheet. In the PDF it is a standard stamp holding the picture.

Select a placed stamp to change its Title, Subtitle and Shape in Properties; Update Fields fills in its date and name again. Stamps are saved as standard PDF stamps that Acrobat and other PDF apps show as drawn.

The options row under the toolbar sets a stamp's Font, Size and Bold / Italic. The title is bold until you turn Bold off, and Italic slants both lines. Size is the size of the title: type a new one and the stamp grows or shrinks about its centre (Properties' Font size is the same). Times and Courier are saved as they look; a Mac font the PDF doesn't name shows in Cella PDF and saves in Helvetica. Picture stamps have no font.

#Signatures

Tools ▸ Signatures ▸ Add Signature… makes a picture of your signature, three ways:

• Draw it on the pad with the trackpad or mouse (and your initials on the small pad, if you like). Clear starts again.
• Type your name and pick a font: the script faces come first, then every font on the computer. Your initials are made from the first letters.
• Image: choose a scan or photo of your signature on white paper (PNG or JPEG). The paper turns transparent; move Remove paper lighter than until only the ink is left.

Choose black or blue ink and Save Signature. It is kept in the Tool Chest under Signatures (with an "(Initials)" entry when you saved initials), ready to place. Click on the sheet to drop it about 1.5 inches wide, or drag to size it. Later, pick it from Tools ▸ Signatures or the Tool Chest. Turn on Tools ▸ Signatures ▸ Date Beside Signature to put today's date next to it; the two move together.

A placed signature is a picture, like a snapshot: other PDF viewers show it, and Flatten makes it part of the drawing. It is not a digital signature. It does not prove who placed it or that the drawing hasn't changed since, and it doesn't fill a PDF's signature fields. Your signatures are kept with your other Tool Chest tools in Cella PDF's settings on this computer, encrypted with a key only your account can use (your login keychain on a Mac, Windows' own data protection, your desktop's keyring on Linux). They never go to a sync project's Project Tools. Exporting a tool set that holds them warns you first, because the exported file keeps them as plain pictures.

To sign a drawing digitally, choose Document ▸ Sign Digitally…. Pick a certificate from your keychain (on Windows, your certificate store; on Linux, a .pfx file), where it goes (over a signature picture you have selected, a box at the bottom right of the sheet, or invisible), and a reason and location if you like. Sign saves the file with the signature. Turn on Lock the document after signing to certify it with no further changes allowed. Document ▸ Signatures… lists a file's signatures, who signed and whether each is still valid.

Getting a certificate. Cella PDF signs with a certificate you already have; it doesn't make one. - For drawings that leave the office, buy a document-signing certificate from a certificate authority that Adobe trusts (IdenTrust, GlobalSign, DigiCert and Sectigo all sell them, usually by the year). Acrobat and other PDF readers then show your signature as valid with nothing to set up on their side. If your licensing board accepts digitally signed and sealed drawings, check which certificates it asks for before you buy. The certificate comes as a .pfx or .p12 file or on a USB token: double-click the file to add it to your keychain (on Windows, your certificate store); on Linux and the iPad, pick the file itself. - For use inside the firm, you can make your own (a self-signed certificate). On a Mac, open Keychain Access and choose Keychain Access ▸ Certificate Assistant ▸ Create a Certificate…: enter your name, choose Identity Type Self-Signed Root and Certificate Type S/MIME (Email), and click Create. It appears in Sign Digitally… straight away. A signature made with a self-signed certificate shows as not trusted in Document ▸ Signatures… and in other PDF readers until the reader chooses to trust it, so ask your IT for one for anything you issue.

#The Tool Chest

The Tool Chest keeps markups you use again and again. Right-click a markup ▸ Add to Tool Chest…, name it, and it appears under Tools ▸ Tool Chest with its colours, text, stamp, subject and layer. Picking it draws more of the same; a grouped markup (a punch key: a circle with its letter) becomes a one-click tool.

Tools ▸ Manage Tool Chest… lists every tool by set. Drag a tool to reorder it or onto another set; drag sets to reorder the menu. Select a tool to rename it or change its subject and default comment (the text each new markup starts with), and see a preview. Duplicate, Delete and Move to Set work on the selection. Importing and exporting tool sets is under Tool sets and markup exchange.

Project Tools (with a synced document): share tools with everyone on the project. In Manage Tool Chest…, select a tool or a set and choose Project Tools ▸ Share with Project…. The tools appear under Tools ▸ Tool Chest ▸ Project Tools for every member while a document of the project is open, and stay there when you are offline. Anyone on the project can share more or choose Remove from Project Tools. If two people change them at once, the later change is kept and the other person is told. Your Atrium server needs the October 2026 release; an older one shows no Project Tools.

#Legends

Markups ▸ Insert Legend… puts a table on the sheet that sums up its markups: a swatch in each subject's colours, the subject, how many there are and their length, area and volume totals.

Choose a title, what to group by (subject, status, author or layer), whether it covers this sheet or every sheet, and which columns to show. The legend keeps itself up to date as you draw, move and delete markups, so it prints right with the sheet.

Select it to change its options in Properties. Untick Live to freeze it as it is (for an issued set) and press Refresh when you want it brought up to date. Drag it anywhere; drag a handle to give it a fixed size, and rows that don't fit end in "n more…". It is saved as an ordinary PDF text annotation, so Acrobat, Preview and other PDF apps show the table too. On a rotated sheet the legend reads upright, at the sheet's top right as you see it, like text you add there.

#Sequences

A sequence numbers boxes as you place them: door tags D-01, D-02, D-03; grid letters A, B, C; RFI 007, RFI 008. Choose Tools ▸ Sequence… and give it a name (Door Tag), a prefix (D-), the start, the step, the padding (2 gives 01, 02) and the format (1, 2, 3 or A, B, C). Then choose whether the boxes are text boxes or callouts. Every click then drops a box with the next value, sized to fit; press Esc when you are done. Keep in Tool Chest saves the tool, so it is one click next time.

The document remembers where each sequence has got to. After a save and reopen the next box carries on (D-05 after D-04), and so it does in both panes of Split View. Boxes a colleague places on a synced document move yours on too. Select a box to see its sequence in Properties: Prefix, Suffix, Format, Next (type a value to jump), Step and Padding. Untick Numbered (sequence) to keep the text as plain text, or tick it on ordinary text boxes to make them a sequence. Renumber ▾ puts a sequence back in order: In Order numbers the boxes in the order they were placed, By Position in reading order across the sheet. If you delete a box from the middle, Cella PDF offers to renumber the ones left.

#Counts

The Count tool (⇧⌥C; Shift+Alt+C) places a symbol at every click and keeps a running total: one count per run of the tool, so start it again for the next kind of thing. Name the count in Subject (Duplex Receptacle) and the Markups List row reads "Duplex Receptacle · Total 14 EA"; legends count it the same way.

In Properties, Symbol chooses what marks each point (a dot, circle, check, cross, square, triangle, diamond, a numbered disc, or a symbol from a tool set), Size sets it in points, and Show numbers writes each point's number beside it. Total shows how many there are, with Select All. To take one point out, select the count, click that point (a ring marks it) and press Delete; the points after it renumber. Option-click or Alt-click a point removes it too.

#Redaction

Bid amounts, personnel notes and client names can be taken out of a set for good, the way Acrobat Pro does it: mark first, then apply.

• Mark text: select it with the Select tool (drag, double-click a word, triple-click a line), then Markups ▸ Redaction ▸ Mark Text for Redaction (or right-click ▸ Mark for Redaction).
• Mark every place a word appears: search for it in the sidebar, then Markups ▸ Redaction ▸ Mark Search Results for Redaction. Applying these marks also removes bookmarks whose titles contain it.
• Mark an area: Markups ▸ Redaction ▸ Mark Area for Redaction, then drag a rectangle over a drawing, a picture, a stamp or a signature block.
• Marks show as red outlines with hatching; nothing is removed yet. Move, resize, delete or undo them like any markup. In Properties give a mark an Overlay text ("REDACTED") and a Colour. They save as standard redaction marks that Acrobat and other PDF apps understand.

Markups ▸ Redaction ▸ Apply Redactions… removes, under every mark:

• text, letter by letter, so the rest of the line stays exactly where it was;
• linework: a line, hatch, fill or curve that crosses a mark's edge is cut at the edge, so the part outside looks as before and nothing of it is left inside (this includes text the drawing program turned into linework, and dashed lines, whose dashes don't shift);
• the letters' shapes in the fonts: when a letter appears only under marks, its outline is taken out of the font embedded in the file, so it can't be recovered from there;
• shadings and gradients, cut out of the mark;
• pictures: the covered pixels are painted in the mark's colour. A JPEG photo partly under a mark is stored again without compression loss (the copy of that picture is larger);
• comments and form fields over a mark.

Each area is painted in its colour with its overlay text. It can't be undone, so it writes a new file ("A-101 redacted.pdf") and your document keeps its marks. Choose Replace the original to rewrite the file itself (the original stays in the .cella folder). Tick Also remove document metadata to drop the title, author and keywords too. When the file has embedded files (attachments: a spreadsheet, a model), the sheet lists them with Also remove the embedded files, ticked.

When it is done, Cella PDF reads the copy back and looks under every mark again. The summary ends with Verified: nothing remains under 7 marks, or says what is still there and on which sheet.

What is not removed: a letter that only just touches a mark (less than about a sixth of it under the mark) stays, visible beside it; a line much thicker than the mark is narrow stays under the paint; bookmarks are only removed for marks made from a search; link targets, page labels and form-field values elsewhere are not searched. Check the copy before you send it (search it for the words you removed).

#Flattening

Markups ▸ Flatten ▸ Flatten Selected and Flatten All draw markups into the sheet itself, so nobody can move or change them; Unflatten takes back what Cella PDF flattened. File ▸ Export ▸ Flattened Copy… (File ▸ Export ▸ Flattened Copy… on Windows and Linux) writes a flattened copy for a contractor and leaves your working file editable.

File ▸ Export ▸ PDF/A-2b Copy… (File ▸ Export ▸ PDF/A-2b Copy… on Windows and Linux) writes an archive copy for record sets: the markups flattened, every font embedded (Helvetica, Times, Courier, Symbol and Dingbats are replaced by matching fonts Cella PDF ships), an sRGB colour profile and the archive metadata. Before anything is saved it lists what it changed and what it left out: links that open programs, scripts, and attached files (tick Keep attachments as PDF/A-3 to keep them; the copy is then PDF/A-3b). A drawing that uses a font which isn't embedded and that Cella PDF has no replacement for (Calibri, say) can't be archived. Cella PDF names the font, and exporting the drawing again with its fonts embedded fixes it. If your archive asks for a validation report, check the copy with a PDF/A validator such as veraPDF.

For a copy that leaves out the internal notes, statuses and authors before it goes outside the firm, see Sending a client-safe copy (File ▸ Send to Client…).

#Forms

Transmittals, RFIs, submittal cover sheets and inspection checklists that arrive as PDF forms fill in place. The status band says how many fields a form has.

• Click a field and type. Tab moves to the next field (and on to the next sheet), Return or Enter commits, Esc puts back what the field had. Check boxes and radio buttons toggle with a click or Space; list boxes take ⌘-click (Mac) or Ctrl-click (Windows and Linux) for several choices.
• Forms ▸ Highlight Fields tints every field (required ones outlined in red).
• Forms ▸ Clear Form… empties the form; Flatten Form… makes the values part of the sheets.
• Forms ▸ Export Form Data… saves the values as JSON or FDF (Acrobat reads FDF); Import Form Data… fills a form from either.
• Calculated and formatted fields work as in Acrobat. Totals, products, averages and simple formulas (Quantity × Rate) fill themselves in as you type, in the order the form sets. Amounts show as currency ("$1,250.00"), percentages as "8.0%", dates, times, zip codes, phone and Social Security numbers in the form's format. A field shows its plain value while you type in it.
• A date field opens a small calendar when you click into it: click a day, or type the date (10/15/2026, 2026-10-15 or Oct 15 2026 all work; it is written in the form's format).
• A value the form doesn't accept (a percentage over its limit, a date that doesn't exist, letters in an amount) is refused with the form's own message, and the field keeps what it had.
• Forms can carry other scripts Cella PDF doesn't run (pop-up messages, custom code). Those fields still fill in; the status band says "(1 script not run)" after the field count, and Properties marks the field.
• Save writes the values into the PDF, so Acrobat, Preview and other PDF apps show them. View-only Cella PDF shows filled-in values but can't change them.

#Measuring

Measuring needs a key or the trial. Measurements are written into the PDF as real measurement annotations, so Acrobat and other PDF apps show the same values.

#Setting the scale

Set the sheet's scale first: Tools ▸ Set Scale…, or click the scale in the status band, and pick a preset (architectural, engineering or metric) or Custom. Or calibrate from the drawing: Tools ▸ Measure ▸ Calibrate (⇧⌥K; Shift+Alt+K), click two points a known distance apart and type the distance (12'-6" works).

Both end with Apply to: this sheet, every sheet of the same paper size (handy when the plans are one size and the details another), or all sheets. Each sheet keeps its own scale; the status band, the sidebar and Properties show the one you are on. A sheet without a scale says "No scale", and the first measuring tool you pick on it asks for one.

For a detail sheet with several scales, Tools ▸ Measure ▸ Scale Region (⇧⌥R; Shift+Alt+R): drag round the detail and pick its scale; measurements that start inside it use that scale. Tools ▸ Remove Scale Regions on This Sheet takes them off.

#The measuring tools

Dynamic Fill (⇧⌥F; Shift+Alt+F) measures a room with one click. Hover inside it and Cella PDF tints the region its walls enclose, with the area by the pointer. Click, and it becomes an ordinary Area measurement (cut-outs, Properties and totals as for one you drew). Fill gap in the options row (0–12 pt, 4 by default) closes door openings narrower than that. If the fill would run out of the room, Cella PDF says the area isn't closed: raise Fill gap, or draw the room with the Area tool. Esc puts the tool down.

#Drawing measurements precisely

• While you draw, a readout by the pointer shows the length and angle of the segment you are drawing and the total so far.
• Hold Shift to keep the segment at 0°, 45°, 90° and so on.
• Points snap to the linework, text and other markups as you draw (see Snapping); hold ⌘ (Mac) or Ctrl (Windows and Linux) to place one free.
• Type a length while drawing a length, polylength, area, perimeter or volume: 12'6, 12'-6 1/2", 6", 3.5m or 350mm, then Return or Enter. The segment is fixed at that length in the direction you are pointing, and you carry on drawing. A plain number is in the sheet's unit. Delete corrects; Esc drops it.
• The Length tool works by dragging, or by clicking at one end and then the other.
• Arcs: with the Polylength, Area, Perimeter or Volume tool, hold Option or Alt and click a point the next segment should curve through, then click where it ends. Select the measurement to bend an arc by its middle handle; Properties' Arcs row has Straighten. Lengths and areas count the true curve.

#Dimensions

Set a length's Style to Dimension in Properties for a drafted dimension: extension lines at both ends, ticks (Slash), dots (Circle) or arrows at the ends, and the value on the line (Text: On the line) or above it (Above the line). Offset moves the dimension line away from what you measured (negative: the other side). Selected, drag the handle at the value to slide it along the line, and the other handle to move the line itself. Acrobat and other PDF apps show the dimension as drawn.

Slope and 3D length. For a pipe run or a roof, type a Slope in Properties for a length or polylength: a ratio (1:12), a percentage (8 %), degrees (4.5°), or a rise as a length (3'-6"). The value then shows the plan length and the true length with the slope, such as 12'-4" (3D 12'-9", 1:12). The Markups List, its CSV and Excel export gain 3D Length and Slope columns (the plan length stays under Measurement), and the totals add the 3D lengths. A rise is the whole run's; one slope or rise applies to every segment of a polylength. Clear the field to make it flat again. When a polylength's legs change grade, select it alone and use the Segments table in its place: give each leg its own slope or rise (blank is flat), or Apply to all. The 3D length is the sum of the legs', and the value says mixed, such as 32'-0" (3D 32'-7 5/8", mixed). Acrobat and other PDF apps still measure the plan length.

#Areas and cut-outs

A stairwell, a shaft or a courtyard shouldn't count in the floor area. Select the area (or volume) and choose Markups ▸ Cut Out from Area, then draw the opening as a polygon: click each vertex and finish by clicking the first or last point again, double-clicking or pressing Return or Enter. With the Area or Volume tool you can also hold Option or Alt on the first click while one area is selected. The hole's area comes off the area (a volume is the cut area times the depth). The cut-out has to lie inside the outline; Cella PDF says so if it doesn't. Cut as many openings as you need.

Properties shows a Cut-outs row with the count, Cut Out and Remove (which gives the area back whole). The perimeter stays the outline's alone; tick Cut-out edges in perimeter to add the openings' edges. The Markups List, totals, legends and the CSV all use the reduced value, and Acrobat, Preview and other PDF apps show the openings. An area with openings from another markup app opens with its cut-outs.

#Custom columns and formulas

Markups List ⋯ ▸ Custom Columns… is the list of columns your office adds to every markup (Ball in Court, Division, Due, Cost Impact). Each column has a name and a type:

• Text; Number, with a Unit (a currency sign shows before the number, LF or SF after it) and Decimals; Choice, a pop-up of the options you list, separated by commas; Checkbox; and Formula.
• A Formula column works its value out from the markup's measurement and its other columns, so a take-off prices itself: area * [Unit Cost]. A formula can use length, area, volume and count (in the units the sheet's scale shows: feet, SF, CY, each), the other columns by name in square brackets, + - * / ^ and brackets, comparisons, and round(x, 2), if(cond, a, b), min, max, abs, ceil and floor. The Insert menu offers them all, and under the formula Cella PDF says at once whether it reads ("✓ The formula reads") or what it can't find. A markup the formula can't be worked out for shows #ERR.

Use + to add a column and − to remove one (its values go when you save). A column keeps its values when you rename or retype it. The columns travel with the file, in the PDF's custom column data that other markup apps read. Fill them in in Properties, or double-click a row of the Markups List. File ▸ Set ▸ Apply Columns to Set… gives every file of a set the same columns.

#Take-offs and the CSV

Sort the Markups List by subject and it becomes a take-off: each subject a group with its count and totals, and number and formula columns summed too (Area 1,133.44 SF · Count 21 EA · Cost Impact $7,000). Filter to total one subject or one sheet. ⋯ ▸ Export CSV… (⇧⌘E; no key on Windows and Linux; the same as File ▸ Export Markups as CSV… on the Mac and File ▸ Export ▸ Markups as CSV… on Windows and Linux) writes every column, with a heading line and subtotals per group and the totals at the end, ready for a spreadsheet. ⋯ ▸ Export to Excel… writes the same take-off as an Excel workbook, with the numbers as numbers and a Totals row that adds up. See The Markups List.

For an estimator's summary, choose File ▸ Export ▸ Take-off Summary… (File ▸ Set ▸ Export Set Take-off Summary… for the whole set). It pivots the listed measurements: a row per subject (or per tool when a markup has no subject) and a column per space, layer, sheet or status (Group columns by; by file too for a set). Each cell is the quantity summed in the units the list shows (LF, SF, CY, EA, or metric). The table adds a Units column, a Total for each row, your number and formula columns (a cost column, say) summed beside it, and a bold Totals row per unit. Save it as an Excel workbook or a CSV. Export to Excel can add the same table as a second worksheet, Take-off, after the markups: pick the grouping under Take-off sheet by in its save panel, or None to leave it out.

#The Markups List

View ▸ Show Markups List (⌥⌘M; Ctrl+Alt+M) shows every markup in the document, under Properties: a swatch in its colours, the subject, then its measurement, comment and status, with the sheet and the author's initials at the right. Click a row to go to the markup and select it; double-click to edit its subject, comments and custom columns. View-only Cella PDF shows the list read-only. The pop-out button at the right of its caption (or ⌥⇧⌘M; Ctrl+Shift+Alt+M) floats the list in a panel of its own, for a second display, laid out as the Markups Table; see The window.

#Sorting and grouping

The ⋯ menu sorts the list As Drawn, By Subject, By Sheet, By Author, By Date, By Status, By Revision or By Space. Sorted by subject, sheet, author, status, revision or space, the markups run in groups, each under a header with its name, its count and, when it holds measurements, its totals (AREA MEASUREMENT · 2 Area 1,133.44 SF). Click a header to fold its group away and again to open it. Click the count to select every markup in the group, for instance to restyle a whole subject at once. Turn Show Group Headers off for a plain sorted list.

A group of markups (a punch key) is one row with "Group of 3" under it; the totals and the CSV still count every markup.

#Filtering and totals

Type in the filter field to show only the markups whose text matches; group names match too ("no author", "revision 3"). The line under the list totals everything listed (Length 191'-6" · Area 1,133.44 SF · Count 21 EA), so filter to total one subject or one sheet. The Filter button beside the field narrows the list by Status, Author or Sheet (pick several, or This Sheet), to Measurements Only, or to what changed since a time. The caption then reads "12 of 40", and Clear Filters shows everything again.

Views. Once the list is sorted, grouped and filtered the way you like, ⋯ ▸ Views ▸ Save View… keeps that arrangement under a name: the sort and grouping, the filter, Changed Since, Show Modified By, Whole Set and the columns. Pick it from ⋯ ▸ Views later, in any document, to put the list back that way. The view in use has a tick. Three come with Cella PDF: Default, Review (grouped by status, with the author and date) and Take-off (only the measurements, grouped by subject with their totals). Save over a view, or a built-in, with Update “Review”. Reset puts a built-in back, and Manage Views… renames and deletes your own. Views travel in profiles, so an office can hand everyone the same ones.

#With the keyboard

Return or Enter shows the selected markups on the drawing. Delete (Del) deletes them (asking first when there are several). Jump between groups with (⌘↑ and ⌘↓; Ctrl+Up and Ctrl+Down); ↑ and ↓ step over the headers. On Windows and Linux F2 edits a row.

#The whole set

With a folder set open, the ⋯ menu starts with This File and Whole Set. Whole Set lists every file's markups at once, with the file name at the right of each row. Sort By Sheet (By File) to group them by file; the totals, group totals and the CSV run across the whole set, each measurement in its own file's scale. Double-click a markup of another file to open that file and go to it.

#Summary PDF, CSV and Excel

• ⋯ ▸ Export CSV… (⇧⌘E; no key on Windows and Linux): every column, grouped as the list is, with subtotals and totals. In Whole Set the CSV starts with a File column.
• ⋯ ▸ Export to Excel… (also File ▸ Export ▸ Markups to Excel…, and File ▸ Set ▸ Export Set to Excel… for the whole set) saves an Excel workbook (.xlsx) of the markups listed, after the filter, with the CSV's columns. Unlike the CSV, its cells are typed. Dates are dates; lengths, areas, volumes and counts get number columns of their own (Length (LF), Area (SF), Volume (CY), Count (EA)); number and formula columns are numbers in their units; and checkboxes are TRUE or FALSE. Excel can then sort, filter and add them up. The header row stays in view as you scroll, the columns are sized to their contents, and a last Totals row sums the number columns with formulas. When the list is grouped, the first column names each markup's group. One worksheet per group in the save dialog adds a worksheet for each group (each subject, sheet, author, status, revision or space) after an All markups sheet, each with its own totals. In Whole Set the workbook starts with a File column. Numbers and LibreOffice open it too.
• File ▸ Export ▸ Markups to DXF… (File ▸ Export ▸ Export Markups to DXF… on Windows and Linux) hands the markups to a CAD program as a .dxf drawing. Choose This Sheet or Every Sheet (one file per sheet, named after the sheet) and whether each Cella PDF layer or each subject becomes a CAD layer. The drawing is in the sheet's real units from its scale, with its origin at the sheet's lower-left corner, so a wall measured 10'-0" is 10 feet long in AutoCAD. A sheet with no scale is written in points, and Cella PDF says so. Lines, polylines, clouds, rectangles and ellipses keep their shapes (arcs as arcs). Text boxes and callouts become text with their leaders, measurements become their lines with their values as text, counts a point and a number at each spot, and stamps and snapshots a box with their name. Colours, line weights and dashes come along; hidden and flattened markups stay out. Each piece carries the markup's id, subject and custom columns as Cella PDF data, and the Spaces come in as outlines on a layer of their own.
• File ▸ Export ▸ Markups Summary PDF… (File ▸ Export ▸ Markups Summary PDF… on Windows and Linux) makes a report with a picture of each markup and its details, comments, custom columns and replies. File ▸ Set ▸ Export Set Summary PDF… does one for the whole set, with a contents page.

#History and Changed Since

Select a markup and Properties ▸ History tells its story: who created it, who changed it and when, each status it went through ("Status set to Accepted"), who replied, and when it moved to another sheet. Cella PDF keeps this in the PDF itself (up to 50 events per markup), so it travels with the file and needs no server. On a synced document the server's record is added (marked ⇅). Markups from other programs show what their own dates and replies say.

In the ⋯ menu, Show Modified By adds who last changed each markup to its row, and a Modified By column to the CSV. Changed Since… lists only the markups created or changed after a date and time, or since the last revision. Markups ▸ Changes ▸ Show Changes Since… does the same and outlines every changed markup on the sheet in orange, so a reviewer sees at a glance what is new since the last issue. Markups ▸ Changes ▸ Clear Changes takes the outlines away.

#The Markups Table

View ▸ Markups Table (⌃⌘M on the Mac), or the table button in the status band, opens every markup as a wide table along the bottom of the window: a column each for Subject, Page Label, Comments, Author, Date, Status, Colour, Layer and Space, then your custom columns. Drag the line at its top to make it taller or shorter (double-click it for the usual height); the × in its bar or the same menu item hides it. Popping the Markups List out puts this table in its panel, so a second display can hold the whole take-off.

• Sort. Click a column's heading to sort by it, again to sort the other way, and a third time to go back to the order the markups were drawn in. Sheets sort the way you read them (A-2 before A-10); markups that tie stay in drawing order.
• Filter. Control-click (or right-click) a heading and choose Filter “Status”…: type in the box to keep only the rows whose cell contains the text, or pick one of the column's values. A filtered heading shows a small funnel, and the bar above the table says which columns are filtered, with Clear Filters beside it. The Markups List's Filter menu (status, author, sheet, measurements only) and Changed Since… narrow the table as well.
• Columns. Drag a heading's edge to widen it and drag the heading itself to move the column. Control-click a heading to hide it, or to tick the columns you want; Reset Columns brings back every column at its usual width. The table button at the top right of the table has the same choices.
• Select and edit. Click a row to go to the markup and select it; Shift- or ⌘-click to select several. Selecting markups on the drawing selects their rows. Double-click a Comments cell to type a new comment (Return saves, Esc puts it back) and a Status cell to choose a status for that row, or for every selected row. Delete deletes the selected markups. Editing needs a key or the trial.
• Views. The table's columns, widths, sort and filters are saved with the list's views (⋯ ▸ Views ▸ Save View…), so a "Review" view can bring back a table sorted by Status with only open items showing. Views saved before the table existed leave the table as it is.

On iPad, ⋯ ▸ Markups Table in the Markups List opens the same table in a sheet over the drawing: tap a heading to sort, choose a column beside the filter box to filter it, and tap a row to show the markup.

On Windows and Linux, View ▸ Markups Table is Ctrl+Shift+M. The table opens between the drawing and the Sheets strip; drag the bar above it to make it taller or shorter. Each column has its own filter field (on Windows under the headings, on Linux above them): type to keep only the rows whose cell contains the text. Right-click a heading to sort, filter, hide or show columns, clear the filters or reset the columns. Cells are not edited in place: double-click a row (or press F2 on Windows) to edit its subject, comments and custom columns in the list's dialog.

#Sets and documents

#Folder sets

File ▸ Open Folder as Set… (⇧⌘O; Ctrl+Shift+O) opens a folder of PDFs as a set. The Set tab of the sidebar lists the files with their markup counts (kept in the .cella folder inside the set's folder, so they show before any file is opened). Click a file to open it in the same window; a file with unsaved changes is saved first.

File ▸ Set ▸ works on every file of the set, with a progress sheet you can cancel. The open file is saved first if it has changes.

• Print Set… and Export Transmittal…: see Printing and Transmittals.
• Export Set Summary PDF…: one report with a contents page and a section per file.
• Export Set CSV…: the Whole Set list as CSV, with a File column.
• Flatten Set…: flattened copies of every file into another folder; your files stay editable.
• Set Status for Selection…: select markups in the Whole Set list (across files), then set their status in one go; each file is saved, nothing else in it changes.
• Apply Columns to Set…: gives every file this file's custom columns (matched by name, so values a file already has stay put).
• Compare Set with Folder…: compares each file with the file of the same name in the other issue's folder (revision suffixes such as _R2 ignored) and clouds the changes on layer Compare.

File ▸ Set ▸ Rename Files from Sheets… names each PDF of the set after its first sheet: its number and title from the Sheet Index, Detect Sheet Numbers or the sheet names. Type a pattern with {number}, {title}, {rev} (the revision from the file's revision schedule, if it has one) and {file} (the name now). The default is {number} - {title}, and characters a file name can't hold become "-". The preview lists every file's current and new name before anything moves. Names in red would collide (two sheets with the same number, or a name already in the folder), and those files stay as they are. Rename moves the files with everything Cella PDF keeps beside them (markup logs, backups, search indexes, sync links) and keeps the Set list's order. An open file stays open under its new name. File ▸ Set ▸ Undo Rename puts the last rename's names back.

#Sheet index

Many sets list their drawings in a table on the cover ("SHEET NO. / SHEET TITLE / REV"). Tools ▸ Sheet Index… reads that table from the first sheets of the open file and shows each row with the sheet it matches by number (in a folder set: any file of the set). Double-click a misread number or title to fix it, and untick rows to leave out (Cella PDF can take another table on the sheet, such as a wall-type schedule, for an index: untick its rows). Then click Apply. Each matched sheet is named by its number and keeps its title, which the Sheets list, the strip and the status band show. Tick Move the sheets into index order to reorder them (in a set, the Set list follows the index). The report lists index rows with no sheet and sheets the index doesn't list. Save to write the numbers and titles into the PDF. In a set, each changed file is saved for you.

#Slip-sheeting

When a new issue arrives, slip-sheet it in and keep every markup:

• File ▸ Slip-Sheet from Newer Issue… replaces sheets with the newer PDF's, matched by sheet number, keeping every markup in place. A one-page PDF with no match offers to replace the sheet on screen.
• File ▸ Slip-Sheet Set from Folder… does it for a whole folder set, pairing each file with the file of the same name in the folder you choose (revision suffixes like _R2 or rev 3 ignored), and reports what it replaced and skipped.

#Page operations

The Sheets menu and a right-click on a row of the Sheets list work on the selected sheets (Shift-click rows, or click them with ⌘ (Mac) or Ctrl (Windows and Linux) held down, to select several), or on the sheet on screen:

• Rotate Right and Rotate Left (⌘R, ⌘L; Ctrl+R, Ctrl+L) turn sheets a quarter turn. Markups and measurements turn with the drawing and keep their values; text you add to a turned sheet reads upright.
• Move Sheet Up / Down, Move Sheet To…, or drag rows in the Sheets list to reorder.
• Insert Pages… adds every page of another PDF after the selected sheet, with its markups, scales and links.
• Extract Sheets… saves the selected sheets as a new PDF with their markups, scales, custom columns and bookmarks; this document stays as it is.
• Insert Blank Page… adds empty sheets; see Blank pages below.
• Insert Image Pages… (also in Document) makes a sheet of each picture you choose; see Blank pages below.
• Delete Sheet… removes sheets and their markups after asking.

Every one of these is undone with Undo (⌘Z; Ctrl+Z) until you close the document, even after saving, within Undo's last 300 steps. On a document connected to a sync project they go to everyone in the project as you make them, and so does their undo: Undo turns, moves, deletes or brings the sheet back for everyone; see Sharing and sync. Blank pages, cropping and resizing travel the same way: everyone gets the blank sheet, the crop or the new paper size, with the sheet's markups, scale, links and Spaces moved with its drawing, and undo takes it back for everyone. Cropping and resizing need an up-to-date Atrium; with an older one a synced document refuses them until you disconnect it (Sync ▸ Disconnect Document). Extract, Split Document and Export Sheets as Images work either way.

#Combining files

File ▸ File Tools ▸ Combine Files… joins several PDFs into one, in the order you set. Add files with Add Files…, drop PDFs onto the list, drag rows to reorder them and Remove the ones you don't want. With a folder set open, Combine the Set lists every file of the set in order. Choose:

• Markups: keep them as markups you can still edit, or flatten them into the sheets.
• Page labels: each file's own sheet names (from the file, or read from each title block), or names made from the file names.
• A bookmark per file, with the file's own bookmarks under it, or a bookmark per sheet when it has none.

Combine… asks where to save ("A-101 combined.pdf") and opens the new file. Every markup comes along exactly as it was, data other apps keep on it included. Layers with the same name become one layer, and form fields with the same name are renamed ("Date_2") so both keep their values. The files themselves are never changed.

#Reducing file size

File ▸ File Tools ▸ Reduce File Size… makes a smaller copy of the document:

• Pictures: Good for sharing (150 dpi, JPEG 80), Small for email (100 dpi, JPEG 65), Custom, or Keep as they are. Scans and photos drawn finer than that, measured by how large they appear on the sheet, are averaged down and stored as JPEG (grey scans stay grey). A scanned set of 90 MB typically comes down to a tenth, and the summary says how much ("31 pictures recompressed: 92.4 MB → 11.8 MB"). Black-and-white (1-bit) scans are stored the way fax machines store them (CCITT Group 4), at their own resolution, or at 200 dpi when they were scanned at more than 400 dpi. They never go below 200 dpi, so linework and small lettering stay legible ("4 black-and-white scans recompressed: 9.6 MB → 1.2 MB"). Drawings made of lines are not pictures and are never touched, nor are pictures with transparency, pictures under 150 KB and JBIG2 scans.
• Clean up stores fonts and pictures that appear several times once, and drops what earlier edits left behind. Flatten markups draws them into the sheets.
• Discard page thumbnails, attached files and other programs' private data (Illustrator keeps a second copy of its artwork in exported PDFs). Cella PDF's own data always stays.

Press Check Size to see "Before 48.2 MB → After 9.1 MB" before anything is written. Then choose Save As… for a copy ("A-101 reduced.pdf") or Replace to make this file the smaller one (a copy of the original is kept in the .cella folder beside it). Markups, links, bookmarks, page labels and measurements stay exactly as they were. Cella PDF reads the smaller file back and refuses to write it if anything is missing.

#Headers and footers

Document ▸ Headers & Footers… puts text at the top and bottom of every sheet, or of a range of sheets: left, centre and right in the header and in the footer. Type text and add these from Insert:

Bates numbers count on from sheet to sheet. Choose the text size and the margin; the preview shows the first sheet. Put them as markups (on the layer Header/Footer: edit, move or delete them like any text box, or hide the layer) or into the page content (they print and show in every viewer like the drawing itself). Applying again replaces the earlier ones. Document ▸ Remove Headers & Footers takes off every header and footer Cella PDF added.

#Splitting a document

File ▸ File Tools ▸ Split Document… makes several PDFs out of the open one. Split by:

• Sheet ranges: type them, such as 1-3, 4-6, 7- (each range is a file; 7- runs to the last sheet).
• Every N sheets: files of 2, 5, 10 sheets.
• Top-level bookmarks: each top-level bookmark starts a file, named after the bookmark.
• Sheet-name prefix: the discipline letters, so A-101, A-102 … go into one file, S-201 … into another, M-301 … into a third.

The list shows every file it will make ("Tower - A.pdf", with its sheets) before anything is written. Choose the folder and what the names start with, then Split. Each file keeps its sheets' markups, bookmarks, scales and custom columns, as Extract Sheets does; the open document stays as it is.

#Blank pages

Sheets ▸ Insert Blank Page… or Sheets ▸ Insert Blank Page… adds empty sheets after the sheet on screen (or before it, at the start, at the end). The size is the sheet on screen's, or any of Arch A–E, ANSI A–E and A4–A0, portrait or landscape. Undo (⌘Z; Ctrl+Z) takes them out again.

Sheets ▸ Insert Image Pages… turns pictures into sheets: choose one or more JPEG, PNG, HEIC (not on Windows) or TIFF files and each becomes a sheet after the sheet on screen (or at the end), named after its file. Each sheet is the picture's own size at the resolution the file gives (a 300-dpi letter scan comes in at 8½ × 11 in; a picture that gives none is taken at 150 dpi, which you can change). You can also choose This sheet's size or a paper such as Arch D, with the picture scaled to fit and centred on white. JPEGs go in exactly as they are, with no loss; a PNG's transparent parts become white. On the Mac you can also drop pictures on the Sheets filmstrip or the Sheets list. Undo (⌘Z; Ctrl+Z) takes them all out again. On a synced document the new sheets reach everyone in the project.

#Cropping and resizing pages

Document ▸ Crop Pages… sets what a sheet shows and prints: trim its margins (top, bottom, left, right, in inches, millimetres or points), crop it to a size, or Remove the crop. Apply it to this sheet, the sheets selected in the Sheets list, or all of them. To draw the crop instead, choose Document ▸ Draw Crop Box (or Draw on Sheet in the sheet) and drag a rectangle over the drawing. Crop Pages opens with the margins it leaves, ready for that sheet or the others (coming from Draw on Sheet, with the units and sheets you had chosen). It works in either pane of Split View showing this document. Markups stay exactly where they are on the drawing; one cut off by the crop comes back when the crop is removed.

Document ▸ Resize Pages… puts sheets on another paper. Scale to fit the paper shrinks or enlarges the drawing (its hatching and fills too) with its markups, and changes the sheet's scale with it, so a wall that measured 12'-6" still does. Keep its size leaves the drawing as it is and grows (or trims) the paper around it, centred or from the top-left corner. Both are undone with Undo (⌘Z; Ctrl+Z).

#Sheets as pictures

File ▸ Export ▸ Sheets as Images… (File ▸ Export ▸ Sheets as Images… on Windows and Linux) saves one PNG or JPEG per sheet, at 72 to 600 dpi, with or without the markups, into a folder you choose: "Tower - A-101.png", "Tower - A-102.png" … Each picture is the sheet as it reads on screen (turned sheets upright, crops applied). A very large sheet at a high resolution is made as large as Cella PDF can draw it (about 15,000 pixels across at most); the sheet says so before you export.

#A stamp on every sheet

Document ▸ Apply Stamp to Every Sheet… puts a copy of a stamp on every sheet, or on the sheets selected in the Sheets list. Select a stamp you have placed first to copy it to the same spot on every sheet (the same distance from the same corner, so one in the title block lands in each title block), or pick a stamp from the list and a corner. A stamp you turned (Markups ▸ Rotate) is copied turned. Each copy is an ordinary stamp you can move or delete, with its own sheet's name and number filled in. One Undo (⌘Z; Ctrl+Z) takes them all away.

#Sealing and signing a set

An issued set is sealed and signed on every sheet, and each board has its own wording. Document ▸ Seal Presets… keeps that as a preset: the seal picture (a picture stamp or signature from the Tool Chest, or Choose File… for a PNG, JPEG or PDF of your seal, which joins the Tool Chest as a picture stamp), your signature picture (Tools ▸ Signatures), the licensee's name, licence number, state and firm, the statement (pick a template and edit it; {name}, {license}, {state}, {firm}, {date}, {sheet} and {file} are filled in on each sheet, and the preview under the box shows the result), where the block goes (a corner of the sheet, how far in, how wide the seal is, the statement's type size), and whether to sign each file digitally with which certificate (Reason, Location, Lock the document after signing, invisible or a box). The templates are generic wording to start from, not any board's rule: check your jurisdiction's requirements.

Document ▸ Seal Set… applies a preset. Choose the preset, whether to seal this document or the folder set, and which sheets: all of them, sheets by number or name (1-3, 7 or A-101), or sheets whose number matches a pattern (A-*, S-1??); Skip cover and general sheets leaves out G, T, CS and 00 sheets and anything titled a cover. Write in place or as copies (a folder for a set, a file for a document; the originals are not changed). Tick Sign each file digitally to sign with the preset's certificate once the seals are on, and Add a verification page to list what was sealed, the licensee and the signature: on the open document it becomes the last sheet, before the signature; for a set or a copy it is written beside the files as Seal Verification.pdf, signed too.

On each sheet the seal sits in the chosen corner (the title block by default), your signature beside it and the statement under both, turned with a turned sheet. On the open document they are ordinary markups in one undo step (⌘Z; Ctrl+Z takes them all off) until you save or sign; a set's files are written as the run goes, with the usual progress and Cancel. Signing is the same as Document ▸ Sign Digitally…: a file that is already signed takes the new signature as an appended update, so the earlier ones stay valid, and a signed file whose changes would need a rewrite is left alone and reported. A preset names its pictures; if one is removed from the Tool Chest, Seal Set says which and Seal Presets… lets you pick another.

#Printing

File ▸ Print… (⌘P; Ctrl+P) opens the Print sheet, also when the trial has ended:

• Printer: your printers; the choices below are remembered for each.
• Sheets: this sheet, all of them, a Range (1-3, 7 or A-101), or the ones selected in the Sheets list.
• Markups: Print markups (in colour), Form fields, and a Markups summary at the end.
• Scale: Fit to paper (a half-size set on 11×17), Actual size (100%) or Custom %; Tile large sheets prints a full-size sheet across several smaller pages with a ½" overlap and crop marks; Auto-rotate to fit.
• Paper: the printer's choice, or Letter, Tabloid, Arch C, D or E when the printer offers them.
• Colour: Colour, Grayscale, or Markups in colour, drawing in grayscale, the review set where red marks stand out on a grey drawing. Print as image under it sends each page as one picture at 150, 300 or 600 dpi, for printers and print shops that stumble on transparency, unusual fonts or very large CAD drawings (in grayscale, black-and-white pages go as crisp fax-style images).
• Copies.

The preview shows the first sheet on its paper. Print… continues to the usual print dialog; Print as PDF… saves exactly what would print. Unsaved markups print without saving the file.

On Windows and Linux the dialog is the same without the preview. On Windows, the print dialog that follows chooses the printer, copies and paper, and its own scale setting decides Fit to paper and Actual size. On Linux the printer, paper, copies and scale go straight to the printer (CUPS).

File ▸ Set ▸ Print Set… is the Print sheet for the whole set (or the files selected in the Set list). The same choices apply to every file, and Sheets of each file (empty for all, or 1 for each file's first sheet) picks the sheets. The files print as one job with a bookmark per file, or tick One job per file. Transmittal cover listing the sheets puts a page first that lists every sheet printed (number, title, revision, file). Print as PDF… saves the whole set as one PDF with the same bookmarks.

#Transmittals

File ▸ Set ▸ Export Transmittal… writes a one-page transmittal: the project (the folder's name), today's date and the drawing index (from Tools ▸ Sheet Setup ▸ Sheet Index…, or the cover of the open file). The index shows which sheets this set includes, in which file and at which revision. Sheets the index doesn't list are added at the end.

#Checking a set before issue

Document ▸ Check Set… reads every sheet and lists what would embarrass you at the contractor's: a detail or section callout that points at a sheet that isn't in the set ("SEE 2/A-502" with no A-502), a detail number its sheet has no bubble for, the same sheet number used twice, a number skipped inside an otherwise consecutive run, a sheet with no number in its title block, sheets the drawing index doesn't list and index rows with no sheet, an index revision that disagrees with the sheet's title block, a revision triangle with no entry in the revision schedule or missing from the sheet's own revision table, and the unresolved markups left on each sheet (anything whose status is none or Rejected; measurements, stamps, legends, signatures and revision clouds don't count). With a folder set open (File ▸ Set) it reads every file of the set; on its own it reads the open document.

Each finding is an Error (fix it before issue) or a Check (it may be fine: a numbering gap, a reference to a sheet another discipline issues, open markups), with its sheet and one plain sentence. Double-click a row (or Go To) to see it on its sheet, with the markups selected where it has some; in a set the right file opens first. Ignore keeps a finding out of the report for good (it is remembered with the document when you save, or in the set's .cella folder); Show Again brings it back, and the Show pop-up lists the ignored ones. Run Again reads the sheets again after you fix things. Export writes the report as a PDF, an Excel workbook or a CSV file, for the issue record or the QA manager.

The reader is deliberately careful: a sheet number only counts as a reference when the set has sheets with those letters and that many digits, written the way the set writes them (A-101, A1.01), or when it follows a detail number or a word like SEE, DETAIL or SECTION; room numbers, grid lines, wall types and standards (ASTM C150, ANSI A117.1) are left alone, and text read by OCR is marked Check rather than Error. It still can't read everything: a scanned set with no recognized text gives it nothing to check, and a detail bubble drawn as linework rather than text isn't seen (then the detail check stays quiet). On the iPad, Check Set… is in the Set menu for a folder set.

#Batch operations

Everything under File ▸ Set ▸ runs file by file across a folder set: summaries, CSV, flattening, statuses, columns, comparing and printing. Each shows a progress sheet ("Summarising 3 of 25…") with Cancel, which stops after the file in hand, and ends with a report of what it did and any files that failed. Slip-Sheet Set from Folder… and Combine Files… with Combine the Set work across the set too.

#Tool sets and markup exchange

Cella PDF works beside the other markup apps your consultants and contractors use: the PDFs it saves are standard PDFs they read, and PDFs marked up elsewhere open in Cella PDF with everything in them. Tool sets travel as .btx files and markups on their own as .bax files.

#What round-trips

• Markups are standard PDF annotations. The private data other markup apps keep on each markup (custom columns, spaces, labels, groups, review states, measurement data) is read and kept, and a markup you didn't touch is saved byte for byte as it was, appearance included.
• Measurements carry the PDF's measurement dictionaries and the sheet's scale (viewports), so other measuring apps read Cella PDF's scales, lengths, areas, counts and volumes, and Cella PDF reads theirs.
• Custom columns are written in the PDF's custom column data, where other markup apps look for them.
• Groups (punch keys) are written as standard grouped annotations and come back as groups.
• Text boxes keep their margin, alignment and line spacing both ways.
• Statuses and replies are the standard review states and threaded replies that Acrobat and other PDF apps show.
• Sheet names are written as page labels, bookmarks as the PDF's outline, links as standard link annotations, stamps as standard stamps.

#Tool sets

Tools ▸ Import Bluebeam Tool Set… reads a tool set file (.btx), or a .zip holding some, as community tool set libraries hand them out. The tools arrive as a set under its name with their colours, line styles, text, stamp names and layers. Punch keys, symbols and other fixed-size tools drop onto the sheet with one click and stay grouped. Picture stamps (trees, people, doors) come in as linework at their size, in their colours (as pictures when they hold text or images). Sequence tools come in as sequences and count tools as Count tools. Tools Cella PDF doesn't draw (file attachments, form fields) are listed as skipped.

In Tools ▸ Manage Tool Chest…, Export "Set" as a Revu Tool Set… writes the set as a .btx for apps that import tool sets, and Export All Sets… writes one per set into a folder. Export Tool Chest… saves everything as a .cella-tools.json for another Cella PDF user; Import… reads it back (or a .btx, or the tool sets in a .bpx profile), skipping tools you already have.

#Exchanging markups (.bax)

Markups ▸ Export Markups… saves the document's markups (or only the selected ones) as a .bax markups file, for apps that import markups, or as a Cella PDF file that keeps everything exactly. Markups ▸ Import Markups… (or dropping a .bax on the drawing) adds markups from either: they land on the same sheets, keep their authors, dates, status, replies and groups, and Undo takes them all back out. When a sheet is a different size (a new issue of the drawing), its markups go to the sheet with the same number.

#What doesn't come across

• Image stamps in a .bax come in as pictures you can move, and file attachments come in as they were (shown in the Markups List, not editable); both keep the picture or file exactly. A turned image stamp shows at the nearest quarter turn in Cella PDF.
• Another app's cloud review sessions and cloud projects don't come across: in Cella PDF, an Atrium server does the sharing (see Sharing and sync).
• Hatch patterns on measurements come in as plain fills.

#Sharing and sync

#Sending a client-safe copy

Firms keep two copies of everything to avoid sending a client the internal notes. File ▸ Send to Client… writes one copy with only what the client should see, and leaves the original exactly as it was.

The sheet asks what they see — comments, replies and column values; the markup statuses; who made each markup; when — all off unless you tick them. Under Leave out, tick the statuses, layers and subjects whose markups should not go at all: Rejected markups are left out from the start, and a layer you have switched off in the window starts ticked too. Markups are either flattened into the sheets, so the drawing shows them and nothing about them can be read or changed, or left editable as markups. A line at the bottom says how many markups go.

Save Copy… asks where ("A-101 for client.pdf" beside the original), and Cella PDF says what went. What you leave out is taken out of the file, not just hidden: the markups, their notes and replies, the authors and dates, the markup history. A text box's or a measurement's own text always stays, since it is part of the drawing. Your choices are remembered for next time. On the iPad, Send to Client… is in the share menu and offers the copy to share when it is made.

Cella PDF's Sync shares a project's drawings and everyone's markups live through an Atrium server: either one your IT runs on the firm's own server or cloud, or one Sorted Solution hosts for your firm at an address such as https://yourfirm.cellapdf.com. Setting one up, inviting people, backups and the rest are in the IT guide, Atrium: the sync server for Cella PDF. This section is about using it.

1. Sync ▸ Join Server…: the server's address and the invite code you were given, your name and email. The token is kept in your Keychain (on Windows encrypted for your account, on Linux in the keyring).
2. Open a document and Sync ▸ Connect Document to Project…: pick the project. If it doesn't have this document yet, Cella PDF uploads it.

From then on, every markup you make reaches the others in the project, and theirs reach you. The status band shows ● project. Work offline freely: changes queue and send when the server is reachable (○ … offline · 3 pending).

What syncs: markups and their replies and statuses; sheets turned, moved, inserted, deleted or renamed (and sheet titles), with their markups going wherever their sheet goes; the custom columns, the sequences and where they have got to, the revision schedule, the bookmarks, and each sheet's scales, hyperlinks and Spaces. A sheet change arrives on everyone's copy as it is made, and their sheets list and thumbnails follow. Undo (⌘Z; Ctrl+Z) undoes a sheet change of yours for everyone too: the sheet turns or moves back, a deleted sheet comes back with its markups and their history, an inserted one goes again, and Redo (⇧⌘Z; Ctrl+Y on Windows, Ctrl+Shift+Z on Linux) does it again. Your undo history (up to 300 steps) stays as sheets move, arrive or go, yours or someone else's. Each step finds its sheet wherever it is now. If someone else deleted the sheet a step was for, that step is skipped and Cella PDF says so ("Can't undo: that sheet was deleted by Sam."). A markup you are still drawing (an area or polyline half clicked out) when sheets move is dropped. If an inserted sheet can't be downloaded at once (the network dropped), Cella PDF keeps trying, and its markups appear with it.

When two people change the same thing at once (both turn the same sheet, rename it, reorder the sheets, or edit the custom columns), the change that reaches the server last stands everywhere, and the person whose change was replaced is told: "Sam turned “A-101” at the same time as you; their turn stands. The sheets were reloaded." If someone uploads a newer issue of the document, sheet changes made on the older one aren't sent ("Your sheet change wasn't sent"): use Sync ▸ Update Sheets from Project, then make the change again. An older Atrium server keeps only markups. On one of those, sheets can't be changed while the document is synced (Cella PDF says so). An older Cella PDF on any server syncs markups only.

• Who else is here: while a document is connected you see the people working in it: each person's pointer on the sheet, with their name in their colour, and a dashed outline round the markups they have selected. In the status band a circle with their initials shows each person who has the document open; click one to go to their sheet. View ▸ Show ▸ Collaborators hides it all.
• Sync ▸ Update Sheets from Project pulls a newer issue someone uploaded and slip-sheets it in.
• Sync ▸ Show Markup History… lists who changed the selected markup and when (Properties ▸ History shows the same with the local record).
• Sync ▸ Disconnect Document stops syncing this document; Forget This Mac's Servers (Forget This Computer's Servers) removes the tokens.

If a hosted server's subscription runs out, the server becomes read-only: Cella PDF says so, your markups stay in your PDF, and nothing more is sent until it is renewed.

Cella PDF also sends your document's markups to the server when you connect and after each save, so the server holds the current state, not only the changes made while synced. This is what lets an assistant ask about them (see Connecting an AI assistant).

The server sees only markup data, sheet changes and document settings (columns, sequences, the revision schedule, bookmarks), the PDFs you choose to upload and pages you insert into a synced document. Without a server, share a file the usual way: the PDF carries every markup, comment, reply, status and its history.

#Connecting an AI assistant

Cella PDF can let an assistant you already use, such as Claude Desktop or Claude Code, read the documents you have open and the folders of drawings you choose. Ask it which markups on a sheet are still open, what a set's quantities add up to, or which sheets changed since the last issue. By default it only reads. If you choose, it can also propose changes, which you approve one request at a time (below). It is off until you turn it on, and it works with a license or during the trial.

1. Open Settings… and click AI Assistants… (see Profiles and settings below), then choose Read only in the Assistants menu.
2. Click Add to Claude Desktop…. Cella PDF makes a small connector file and opens it with Claude Desktop, which asks you to confirm the install. For Claude Code, VS Code, Cursor and other assistants, click Copy Setup… instead: it offers the Claude Code command line, the entry for a JSON configuration file and VS Code's entry, each with a Copy button.
3. Ask your assistant a question about your drawings. The first time one connects, Cella PDF tells you so; after that the status band shows "Claude connected" (or the assistant's own name) while it is working.

Read and propose changes. Choose Read and propose changes in the Assistants menu and an assistant can also suggest work: clouds, callouts, notes and highlights on a sheet, a status for markups, a reply, values for your custom columns, an Excel or summary export, and a transmittal. It never changes anything on its own. Every change comes to you first in a sheet titled "assistant wants to change document", listing each change with Deny and Allow. Nothing happens until you click Allow; Deny, or no answer within ten minutes, drops the request.

• An allowed change to an open document is one step: Edit ▸ Undo takes it all back. The markup history shows it as "you via assistant".
• A status change across a whole set also saves the files of the set that are not open. Those cannot be undone; as with Set Status, Cella PDF keeps a .bak beside each file it changed.
• An export lands next to the document (or in the set's folder) as a new file and never overwrites one that is there; a second export gets a number in its name.
• Set-wide requests read a file that is open in a window as you last saved it.

Windows and Linux. The feature is the same there. On Windows open File ▸ Options… and click AI Assistants; on Linux open File ▸ Settings… and click AI Assistants…. The pane has the same Assistants menu, sheet-pictures switch and Folders. There is no Add to Claude Desktop… on those systems: click Copy Setup… and use the lines it gives. For Claude Code, run in a terminal (the path is that of your installed Cella PDF):

• Windows: claude mcp add --transport stdio cella -- "C:\Program Files\Cella PDF\CellaPDF.exe" --mcp
• Linux: claude mcp add --transport stdio cella -- /path/to/Cella --mcp

Copy Setup… fills in the real path for you, so copy the line from there rather than typing it.

What the assistant can see. The documents open in your windows (with edits you have not saved yet), the folder sets open in windows, and the folders you add in the pane. It reads markups, their statuses, comments and replies, quantities, the sheet text, the sheet index and revisions, and can compare two issues of a set. It never reads other files on your computer, and it is never told where on your disk a file lives. Pictures of the sheets are a separate switch, Let assistants see sheet pictures, and it is off.

Watching what it does. Window ▸ AI Assistant Activity lists every request an assistant makes, newest first: when, which assistant, what it asked for and which documents it touched. Setting the menu back to Off ends the connection at once.

What leaves your computer. Cella PDF itself sends nothing anywhere: no account, no upload. But the assistant is a separate app, and what it reads from your drawings it may send to its own service to answer you, under that service's own privacy terms. Turn it on only for assistants and drawings you are comfortable sharing that way. Text on a drawing is handed over as plain data; an assistant is told not to follow instructions that happen to be written in a markup.

#Through your firm's Atrium server

The setup above is for assistants on your own computer. An assistant that runs elsewhere, such as a connector in claude.ai or Claude Desktop, can't reach your computer, so it can use your firm's Atrium server instead, if your administrator has turned that on (IT guide: AI assistants). It is read-only.

1. In the assistant, add a connector with the server's address followed by /mcp (https://yourfirm.cellapdf.com/mcp). The assistant shows an eight-character code such as K7QM-4XD2.
2. In Cella PDF, with a server joined, choose Sync ▸ Approve AI Assistant Sign-in…, enter the code and approve it. The code lasts ten minutes. Nobody can sign an assistant in without a person doing this in the app.
3. Ask the assistant about your projects: which markups are still open, who changed what since Monday, where a word appears in the markups.

The assistant can read the projects you belong to: their documents, markups, replies, statuses and history, as the server last had them. It sees no drawing pictures and no sheet text, and it can't add, change or delete anything. A document shows up fully once it has been connected and saved in Cella PDF. Your administrator can see every assistant that is signed in on the server's admin page and Revoke it there, any time. Ask them if you no longer want an assistant to have your projects.

#Profiles and settings

#Settings

Cella PDF ▸ Settings… (⌘,; Ctrl+, in File ▸ Options… on Windows and File ▸ Settings… on Linux):

• Author name: written into every markup you make.
• Appearance: System, Light or Dark.
• Default scale: the scale new sheets start with.
• Autosave: Off, or every 1, 2, 5 or 10 minutes; see Troubleshooting and recovery.
• Author shown as: full name or initials, unless a firm standard locks it.
• Compact files: Never, or after 10, 25 (the default), 50 or 100 appended saves the file is written whole again (see Saving keeps signatures valid).
• Panel rows (Comfortable or Compact) and Right column (Properties on top or Markups List on top).
• Reopen documents at launch, Open documents in tabs, Automatically check for updates, Check spelling while typing and Recognize text on scanned sheets automatically.
• Profile and Firm profile: see below.
• Keyboard: Shortcuts…: change any command's keys; see Changing shortcuts.

Tool defaults (colours, widths, fonts) are remembered as you change them in the toolbar. Whether the Welcome window appears at launch is the checkbox on the Welcome window itself; Invert Drawing, Snap to Drawing and the Snap pull-down's checkboxes are remembered from their menus.

#AI Assistants

Settings… ▸ AI Assistants… is the pane for connecting assistants (how it is used is under Sharing and sync, above).

• Assistants: Off (the default; no assistant can connect), Read only (assistants read documents, sheets and markups) or Read and propose changes (assistants may also propose changes, each of which you allow or deny in a sheet).
• Let assistants see sheet pictures: off by default. While it is off, an assistant gets text and markups, never an image of a sheet.
• Folders: folders of PDFs an assistant may read besides what is open in windows. Add… takes one or several; Remove takes one away.
• Add to Claude Desktop… (Mac only) and Copy Setup… connect an assistant.

If your firm's profile sets AI Assistants, the mode, the pictures switch and the folders show Set by the profile's name and cannot be changed; the connect buttons still work. Without a license or the trial every control is off.

#Profiles

A profile is your setup in one file: your Tool Chest's tool sets, your stamps, custom columns, status values, layout (where the sheets and panels go), defaults (tool styles, autosave, the Welcome window, Invert Drawing), units (default scale and presets) and the keyboard shortcuts you changed. A firm makes one so everyone works the same way.

• File ▸ Profiles ▸ Export Profile… asks for the profile's name and your firm's, and whether to include your signatures' pictures (off unless you tick it: a profile is meant to be shared).
• Import Profile… shows what the file holds with a checkbox for each part. For tool sets, columns and keyboard shortcuts, choose Replace (the profile's instead of yours) or Merge (yours stay, the profile's new ones are added; for a shortcut you both changed, the profile's). Before anything is replaced, your current setup is saved as the profile Previous Settings, so you can switch back. It also reads a .bpx profile (with a drawing open): its tool sets, custom columns and Markups List layout, the rest listed as not carried (see Coming from Bluebeam Revu).
• Imported profiles are listed in File ▸ Profiles with the active one ticked; choose another to switch to it. Manage Profiles… saves the current setup as a new profile and duplicates, renames, deletes, activates and reveals them. Add Profile Columns to Document gives the open document the profile's custom columns it doesn't have yet.

A firm profile. In Settings, Firm profile ▸ Choose… picks a profile on the office's shared drive. Cella PDF applies it then, and again at launch whenever the file has changed, so the office can push new tools. The firm's tool sets replace the ones of the same name and your own sets stay. Columns and the firm's shortcuts are added (your other shortcut changes stay), and layout, defaults and status values follow the firm's. The active profile shows in Settings and on the Welcome window.

#Firm standards

A profile can carry the firm's standards: a style sheet so every seat marks up the same way. They cover each tool's look (colour, fill, width, opacity, line ends, cloud, font, size, bold, italic, alignment), the nine hot colours, the Subject and Status values (and whether other values are allowed), the default scale and depth unit, how measurements read (feet and inches to 1/16", millimetres…), whether authors are written as full names or initials, header & footer presets, the firm's stamps, legend templates, and the profile's tool sets.

Each item can be locked. A locked value is enforced: you see its control, but it is disabled and says "Set by <profile>" (in Properties, the options row under the toolbar and the tool palette's STYLE column); new markups take it whatever you pick. An unlocked value is only the firm's default, which you may change.

• Making them: File ▸ Profiles ▸ Manage Profiles…, select the profile, and use the Standards table under the list. Capture Current Defaults takes your Mac's tool styles, colours, status values, scale, author rule, stamps and last-used headers and legend into the standard. Edit… (or double-click) changes one item; for a tool's style, pick the tool and set its colour, width, font and so on with the same controls as the options row. Tick Locked for what every seat must follow. Changes are saved to the profile at once; export it or put it on the office drive as the firm profile.
• Using them: importing or switching to a profile that has standards (or the firm profile changing) applies them. Apply to This Mac in the Standards table does it by hand. Each launch puts locked values back. Settings shows Standards: <profile> and the Welcome window's profile line does too. A profile without standards leaves yours as they are.
• Apply to Document gives the open document the profile's custom columns and gives sheets without a scale the default scale. Subject and Status lists stay in the profile: a PDF has no place for them.
• Headers & Footers… and Insert Legend… offer the firm's presets and templates in a popup (locked: only those). With the stamps locked, Create Stamp is off: use the firm's stamps.
• Settings ▸ Author shown as chooses full name or initials, unless the standard locks it.

#Keyboard shortcuts

Help ▸ Keyboard Shortcuts (⌘/; Ctrl+/), or the ? at the right of the status band, lists every shortcut over the drawing, with a filter field; Esc closes it. The full list, for both, is the appendix at the end of this guide.

Single-key tool shortcuts (V, R, T, ⇧⌥L; Shift+Alt+L…) work only while the drawing has the keyboard, never while you type in a field. ⌃Tab (Mac) or Ctrl+Tab (Windows and Linux) moves the keyboard between the sheets, the drawing, Properties and the Markups List (⌃⇧Tab or Ctrl+Shift+Tab goes back); the panel that has it shows a blue ring round its heading. In the toolbar the arrow keys move between buttons and Space presses one. Every button and list is named for VoiceOver, Narrator and Orca.

#Changing shortcuts

The keys in this guide are the defaults. Cella PDF ▸ Settings… ▸ Shortcuts… (or Customise… at the top of the shortcut list) lists every menu command and every tool, grouped as the menus are, with a search field. Click a command's shortcut and press the new keys; Esc cancels and Delete leaves the command without one. ↺ puts one command back and Restore All Defaults puts them all back. Nothing changes until you click OK; then the menus, the toolbar's tooltips, the tool buttons, the command palette and the shortcut list all show the new keys.

• In the Mac's editor, a menu command's shortcut needs ⌘ or ⌃ (or is a function key such as F5). A tool's key is a single letter or digit, with ⇧ or ⌥ if you like, and works while the drawing has the keyboard.
• If another command already has the keys, the row names it in orange with a Reassign button; only Reassign moves the keys (the other command is then left without any).
• On the Mac, ⌘Q, ⌘W, ⌘H, ⌥⌘H and ⌘, can't be changed, and neither can the keys macOS keeps for itself (⌘Tab, ⌘Space, ⇧⌘3 and the other screenshot keys, ⌃ and the arrow keys…) or ⌃Tab, which moves between panels.
• Your changes travel in a profile (Export Profile…), and a firm profile can set them for everyone.

Windows and Linux have the same editor under Settings (Options on Windows), Keyboard: Shortcuts….

#Mac, Windows and Linux keys

Most keys match: ⌘ on the Mac is Ctrl on Windows and Linux, ⌥ is Alt and ⇧ is Shift, so ⌘S is Ctrl+S and ⇧⌥L is Shift+Alt+L. These are the keys that don't follow that rule:

On Linux, Ctrl+Alt+T is left to the desktop (it opens a terminal), which is why the tool palette is Ctrl+Shift+T on Windows and Linux alike.

#Troubleshooting and recovery

#Saving can't lose your file

Save (⌘S; Ctrl+S) writes the PDF to a temporary file next to the original, reads it back to make sure it is a complete, valid PDF, and only then swaps it in. If anything goes wrong (the folder is read-only, the file is locked or open in another program, the disk is full, the copy doesn't read back the same), your file stays exactly as it was. The document stays open with your markups in it, and an alert says why: "Couldn't save “A-101.pdf”". Use File ▸ Save As… to put a copy somewhere else. While a save hasn't worked, Cella PDF won't close the window or switch to another file of the set, so nothing is dropped on the way.

The first save of a session also keeps the original in the .cella folder next to the file (.cella/<file>.bak), and every save adds to a log of the markups there.

#Saving keeps signatures valid

When you save a file you opened from disk, Cella PDF adds your changes to the end of the file and leaves everything that was already there exactly as it was, as Acrobat does. Saving is quick even on big sets, and a digitally signed drawing stays signed: the signature still covers exactly what was signed, and a reader that checks signatures shows it valid, with your markups as changes made after signing.

Saving an encrypted or damaged file rewrites the whole file instead, and so does changing the sheets of a signed file (rotating, moving, inserting, deleting, cropping or replacing them, flattening, headers and footers). Then Cella PDF asks first: Save Anyway rewrites it (the signature is no longer valid), Save a Copy… saves your changes to a new file and leaves the signed one as it is, and Cancel saves nothing.

Earlier versions stay inside the file until it is rewritten (Cella PDF does that by itself every 25 saves, or when you choose File ▸ File Tools ▸ Compact File, but never to a signed file), so a markup or a sheet you deleted can still be found by PDF tools. To hand out a file without them, use File ▸ Export ▸ Flattened Copy… or File ▸ File Tools ▸ Reduce File Size.

#Autosave and crash recovery

While a document has unsaved changes, Cella PDF writes them every two minutes to a recovery copy, .cella/<file>.<code>.autosave.pdf next to the file, where the code stands for your computer and user name (or, if that folder can't be written, in Cella PDF's own application data folder). Your file itself is not touched. Each person gets their own recovery copy, so a colleague who opens the same drawing from a shared project folder is never offered your unsaved changes, and their saving or closing it never deletes yours. Saving, reverting or closing the document cleanly deletes the recovery copy.

If Cella PDF ends unexpectedly, the next time you open that file, or start Cella PDF, it asks "Recover unsaved changes from Today at 14:32?" Recover opens them as unsaved changes to the file (save to keep them); Discard deletes the recovery copy and opens the file as it is on disk. Choose how often under Settings ▸ Autosave: Off, or every 1, 2, 5 or 10 minutes. View-only Cella PDF doesn't save, so it doesn't autosave either.

#Encrypted and protected PDFs

A PDF that is encrypted but opens without a password (RC4, AES-128 or AES-256, which is how most "owner password only" files come) opens normally, and a save writes it back encrypted with the same protection and permissions. If its permissions forbid adding or changing comments, Cella PDF opens it read-only and tells you once: ask the sender for a copy without that restriction. A PDF that needs a password to open can't be opened in Cella PDF. Cella PDF says so; ask whoever sent it for an unprotected copy.

#Read-only files and folders

A file you can't write to (locked in the Finder, read-only on a server, in a folder you can't write in) opens normally and you can mark it up, but Save says why it can't, before anything is written: "You don't have permission to save in the folder “Issued”". Use File ▸ Save As… to save a copy somewhere you can write. The recovery copy goes to Cella PDF's own folder instead.

#Other things to try

• The keys don't pick tools. Tool keys only work while the drawing has the keyboard: click the drawing (or press ⌃Tab on the Mac, Ctrl+Tab on Windows and Linux, until it has the blue ring) and try again.
• The sidebar covers the drawing. Below 1280 points wide the sidebar floats over the drawing; click the pin at the top of it to dock it, or choose View ▸ Layout ▸ Panels Overlay ▸ Never.
• A measurement reads "No scale". Set the sheet's scale (Tools ▸ Set Scale…) or calibrate.
• A damaged file. A damaged list of annotations doesn't stop a file opening; if a file won't open at all, Cella PDF says why. Send it to us with Help ▸ Report a Bug….

#Getting help

• Help ▸ Cella PDF Help (⌘?; F1) opens this guide in its own window, with a search field and the contents at the side. Help ▸ Online Documentation opens the same guide on the website, where it may be newer.
• Help ▸ What’s New lists what is new in every version of Cella PDF, newest first, with the versions down the left side; a version that also fixed things ends with “+ bug fixes”.
• Help ▸ Report a Bug… (⌥⌘B; Ctrl+Alt+B) sends us a report: see Reporting a problem below.
• Help ▸ Check for Updates… (on the Mac, Cella PDF ▸ Check for Updates…) looks for a newer version. The daily automatic check sends only the app's version, whether a trial or a license is active, and the system version, and can be turned off in Settings.

Cella PDF keeps no account and sends no documents, markups or usage data anywhere, except a report you send yourself with Help ▸ Report a Bug…. Sync talks only to your firm's Atrium server. AI Assistants is off until you turn it on, and the only assistant that can read anything is one you bring in yourself: you authorize it, you connect it, and what it does with what it reads is between you and that assistant, under its own terms, not ours. Cella PDF and Sorted Solution send nothing to any assistant on their own. Window ▸ AI Assistant Activity lists every request an assistant makes.

#Reporting a problem

Help ▸ Report a Bug… (⌥⌘B; Ctrl+Alt+B) opens a short form: the type (a bug, something that looks wrong, a feature request or a question), a one-line title, what happened, what you expected, the steps if you know them, and your email so we can reply. Three boxes choose what goes with it, and What is sent lists it exactly before you send:

• Include a screenshot (on): the window as it was just before the form opened, with a preview and Retake; on the Mac and Windows you can send the whole screen instead.
• Include diagnostics (on): Cella PDF's version and license state (never your license key); your computer's model, system version, displays, language and free disk space; and your settings (not your name, and no folder paths). For the open document it adds its name, size, page count and sheet sizes, never its content, with the last 300 lines of its save log in the .cella folder. It also adds the system's record of Cella PDF's last crash, if there is one newer than your last report.
• Include this document (off): the PDF itself. Tick it only if you may share the drawing with us; we use it to find the bug and delete it after. Files over 200 MB can't be sent this way: say so in the report and we'll send you a link.

On the Mac, Send opens Mail with everything attached (if you use another mail app, the report is saved on your Desktop as a zip and an email opens for you to attach it to). On Windows and Linux the zip is saved on your Desktop and an email to support@sortedsol.com opens; Reveal shows the zip. A copy of every report stays on your computer: Help ▸ Previous Bug Reports lists them. If Cella PDF crashed the last time it ran, it asks at the next start whether to send the crash report (Send, Not Now or Never Ask).

After a crash. Cella PDF keeps its own short record of a crash on your computer: what went wrong, its version, the open documents' file names, sizes, sheet and markup counts (never their folders or content), how much memory it was using, and the names of the last 50 commands and tools you used. Nothing is sent by itself. At the next start, Send… (or Help ▸ Report a Bug… later) opens the form with the record attached, and What is sent lists it before anything goes. The records are in ~/Library/Logs/Cella on the Mac, %LOCALAPPDATA%\Cella\Crash on Windows and ~/.local/state/cella/crash on Linux; the newest ten are kept. Unsaved changes are kept by autosave and offered back when the document opens again (see Autosave and crash recovery).

If the drawing view itself stops (on a very large set, or when the system runs short of memory), Cella PDF restarts it and opens the document again, offering back any changes autosave kept. If it stops more than three times in a minute, the window closes instead and says so; the file is not changed. On Windows, an unexpected error that Cella PDF can survive asks whether to Continue (save your work soon) or Quit.

On the iPad, Report a Bug… opens a mail to support instead of the form; see Reporting a problem in Cella PDF on the iPad.

#Coming from Bluebeam Revu

If you have used Revu for years, most of Cella PDF is where you expect it, and the PDFs go both ways: Revu's files open in Cella PDF with their markups, and what Cella PDF saves is read by Revu (see Tool sets and markup exchange). This section is a map: what each Revu feature is called in Cella PDF and where to find it, the keys, and what to do with your Revu files. Most of it needs a key or the trial. A view-only Cella PDF views, searches and prints (see One product, one key).

#Revu to Cella PDF, feature by feature

#Keys

Cella PDF uses Revu's single-letter tool keys, so a tool's key is the same: press it while the drawing has the keyboard. The Mac and the Windows and Linux keys are the same letters; where a key takes modifiers, ⇧ is Shift and ⌥ is Alt, so Length is ⇧⌥L on the Mac and Shift+Alt+L on Windows and Linux.

Most menu keys match: ⌘ on the Mac is Ctrl on Windows and Linux and ⌥ is Alt. The ones you will reach for, with the exceptions:

If a key isn't the one you are used to, change it: Cella PDF ▸ Settings… ▸ Shortcuts… lists every menu command and tool, and Help ▸ Keyboard Shortcuts (⌘/; Ctrl+/) shows the keys you have now (see Changing shortcuts). The whole list is the appendix.

#What to do with your Revu files

• Drawings with markups. Open them. Revu's markups, measurements, scales, replies, statuses, groups and custom column values are read and kept, and a markup you don't touch is saved as it was.
• Tool sets. In Revu, Tool Chest ▸ Manage Tool Sets ▸ Export makes a .btx. In Cella PDF choose Tools ▸ Import Bluebeam Tool Set… (or Import… in Tools ▸ Manage Tool Chest…). Do this for each set, including your punch keys.
• Profiles. Export the profile from Revu (a .bpx), open any drawing in Cella PDF and choose File ▸ Profiles ▸ Import Profile… with the .bpx. Cella PDF reads its tool sets (each its own set), its custom columns (text, number, choice list, checkmark and formula columns; a date column becomes text, and a formula Cella PDF can't read is kept as a text column with a note) and its Markups List layout (saved as the view "Revu: profile name"). The import sheet shows them with a checkbox each before anything is installed. It also lists what is not carried: toolbars, keyboard shortcuts, Studio settings and stamps. To take only the tool sets, give the .bpx to Tools ▸ Import Bluebeam Tool Set…. Then save the setup with File ▸ Profiles ▸ Export Profile… so the office can share it, or put it on the shared drive as the firm profile (Profiles and settings).
• Custom columns. The columns on your markups are read from the PDF. Markups List ⋯ ▸ Custom Columns… shows them, and File ▸ Set ▸ Apply Columns to Set… gives every file of a set the same ones.
• Exchanging markups. Markups ▸ Export Markups… writes a .bax that Revu imports (Markups ▸ Import in Revu), and Markups ▸ Import Markups… reads one.
• Cut-outs. An area's openings are read and written, so an area with cut-outs keeps them both ways.
• Studio Sessions and Projects. A PDF you have from them opens like any other; in Cella PDF, sharing between people is done with an Atrium server (Sharing and sync).

#Cella PDF on the iPad

Cella PDF for the iPad opens the same PDFs and writes the same markups as the Mac, and the files go back and forth without conversion. This chapter covers only what differs on the iPad; the tools, measuring, the Markups List and the Tool Chest work as described in the rest of this guide. Keys on the iPad are for a Magic Keyboard, and are written as on the Mac (⌘Z); Settings ▸ Keyboard changes them.

Opening drawings. Cella PDF shows the Home when it starts: a Recent row, the sample set, and the license status. Open brings up the Files browser, so a drawing can come from On My iPad, iCloud Drive or any provider Files shows (Dropbox, OneDrive and so on). You can also open a PDF from another app with Open in Cella PDF, or tap Share ▸ Cella PDF in Files or Mail. Cella PDF keeps the drawing where it is and saves through Files, so an iCloud file stays in iCloud. A .bax opened this way goes into the drawing that is open; a .btx goes into the Tool Chest. A picture (JPEG, PNG, HEIC or TIFF) picked in the browser, opened with Open in Cella PDF or dropped on the Home becomes a new one-sheet PDF in On My iPad ▸ Cella PDF, named after it (site-photo 2.pdf when site-photo.pdf is taken), and opens; the picture stays as it was. Open the sample drawing on the Home opens A-101, the clinic floor plan used for the pictures in this guide.

The trial and buying. The 14-day free trial starts the first time you open Cella PDF, with no sign-up. The pill at the top of a document counts the days. When it ends, Cella PDF is view-only, as on the Mac. You can open, read, search and print, and the Cella PDF sheet explains how to carry on. Two ways to buy: - Buy Cella PDF… (on the Home, and on the sheet) is the App Store purchase: one payment through your Apple account. - Enter License Key… takes a key you already have, including one bought for another platform. One key covers one computer (Mac, Windows and Linux) and one iPad. Restore Purchases, on the license screen, brings back an App Store purchase on a new or erased iPad. Deactivate This Device… frees the iPad's place on a key.

Touch and Apple Pencil. - One finger draws with the tool you have chosen. With Select it selects what it touches and pans the sheet when it touches nothing. - Two fingers pan and pinch, about the point between them. A double-tap fits the sheet. - A long press opens the menu a right-click gives on the Mac. Long-press a tool in the palette for its variants. - The Pencil draws with pressure on the Pen, and a resting palm is ignored while the Pencil is down. - A stroke drawn with pressure is one smooth line that swells and thins with the pressure, with round ends. It looks the same in the saved PDF and in other PDF readers, and stays sharp at any zoom. - Settings ▸ Apple Pencil ▸ Only Apple Pencil draws turns on by itself the first time you use a Pencil. With it on, a finger pans and zooms the sheet and only the Pencil draws; Select still selects with a finger. Turn it off to draw with a finger again. - A tap with the Pen leaves a dot, for a decimal point or a spot level. A click with the Pen on the Mac and Windows does the same. - The Pen stays chosen from one stroke to the next, so you can write a line of notes without choosing it again. - The Eraser (in the palette) removes pen and highlighter strokes: drag across them, and one drag is one Undo step. The Pencil's eraser end does the same, and a double-tap on the Pencil's side goes to the Eraser where the Pencil settings say "switch to eraser". Otherwise a double-tap returns to your last tool.

Undo and Redo. The two arrows in the top bar undo and redo the last change. They are grey when there is nothing to undo, and hidden while Cella PDF is view-only. A two-finger tap on the sheet is Undo and a three-finger tap is Redo. On a hardware keyboard ⌘Z and ⇧⌘Z do the same; while you type in a text box they stay out of the way and undo the typing instead.

Keyboard. A Magic Keyboard (or any hardware keyboard) picks tools with the Mac's letters: V for Select, R for Rectangle, P for Pen, H for Highlight, T for Text Box, and the Shift and Option ones such as ⇧C for Revision Cloud and ⇧⌥L for Length. The tools the palette doesn't have are left out; the Mac's list is in the appendix. Backspace and forward Delete (⌫, ⌦) delete the selected markups. All of these step aside while you type in a text box or a field, and while a sheet is open over the drawing, so an R typed into a note is an R. Hold ⌘ to see every key listed, and change any of them in Settings ▸ Keyboard.

The panels. The sidebar at the left has Sheets, Search, Layers, Trace Paper, Bookmarks, Markups List and Tool Chest tabs, as the Mac's sidebar does; tap a sheet to go to it. Trace Paper (also View ▸ Trace Paper ▸ Trace Paper Panel) is where you add, pick, hide, move and turn trace sheets to sketch over the drawing with the Pencil (see Trace Paper earlier in this guide). The tool palette floats over the drawing: drag it to any edge and it stays there. The options bar above the drawing shows the active tool's colour, line, fill and opacity. Properties opens from the selection or from the options bar and changes every selected markup at once.

Search, Replace and Visual Search. The Search tab searches the drawing's text and the markups together; the menu at the right of its field has Match Case, Whole Word, Regular Expression and, with a folder set open, Whole Set (see Search). The same menu holds Replace… and Visual Search…: - Replace… adds a Replace with row to the Search pane. Replace changes the matching words in the markup of the result shown and moves to the next one. Replace All first says how many matches in how many markups it will change, and asks. They change markup subjects, comments and replies, not the drawing's own text, measurements or stamps, and leave locked markups alone. Each is one Undo step. - Visual Search…, or Visual in the pane's Text / Visual switch, finds a symbol by how it looks. Tap Pick Symbol, then drag a box around a door swing, a receptacle or a fixture tag with a finger or the Pencil (a finger works here even with "Only Apple Pencil draws" on). A bar over the drawing says "Drag a box around a symbol on the sheet", with Cancel. The places that look the same are listed by sheet and outlined on the drawing; tap one to go to it, or step through them with ⌘G and ⇧⌘G. Match (60 to 95 %) says how alike a place must be, Rotations also finds the symbol turned, Size ±10 % finds it a little smaller or larger, and All Sheets looks on every sheet instead of the one you are on. Change any of them while symbols are shown and the search runs again. Place Counts puts a Count markup on every symbol found, one per sheet, and Mark for Redaction covers each with a redaction mark. One Undo takes either back. See Search.

More tools in the palette. The palette also holds the tools the Mac has under Markups and Tools. On the iPad you draw them on the sheet, and a sheet asks what is left: - Link draws a rectangle, then asks what a tap on it does: go to a Sheet (fitting the page, keeping the zoom, or Show a region that you drag out on that sheet), show a Snapshot View (pan and zoom the sheet where you want it, then Use This View), open a Web Address, or open a File at a page. Border (No border, Underline or Box) and Colour say how the link looks on the sheet. The last ones you chose start the next link, and Properties changes them for a link already drawn. Double-tap a link with the tool to edit it. See Links. - Space closes a room and asks for its name. See Spaces. - Scale Region draws an area that has its own scale. See Setting the scale. - Draw Crop Box draws the box to keep, then asks for the margins and what Apply to: this sheet, the sheets the same size as it, the sheets you chose in the Sheets pane, or all sheets. Crop… in a sheet's menu asks the same. See Cropping and resizing pages. - Legend and Revision Tag are placed with a tap, not drawn: the legend asks for its options first, and the tag is numbered with the current revision. When your firm's standard has legend templates, the legend's Template menu lists them (and offers only them, with the rest of the sheet greyed, if the standard locks them). Drag either into place; Properties opens on its rows. - Redact marks an area for redaction (below), and Take Photo places a site photo (below).

Settings. The Home's gear and View ▸ Settings open Settings: Author, Units and Scales, Snapping, Apple Pencil, Take Photo, Scanned Sheets, Saving, Keyboard, Profiles and Help. Keyboard lists the shortcuts, tool keys included, and takes new ones. Profiles has Export Profile… and Import Profile…, which read the same profile file as the Mac. A firm's standards in it, such as legend templates and locked tool styles, apply once it is imported (see Firm standards). Help has the User Guide, What’s New, Report a Bug… and Delete Diagnostics, which says how many reports are kept (see Reporting a problem, below). Reset Cella PDF… at the end puts every setting back; your documents, Tool Chest and license stay.

Windows. Each document opens in its own window. With Stage Manager you can put two side by side, or move one to an external display. Split View shows two sheets in one window, as described under Split View. Closing a window saves the file.

Printing. Print opens a Cella PDF sheet of options before AirPrint's own: - Sheets: all, this sheet, a range (1-3, 7, or sheet names), or Choose Sheets…. - Print markups, Form fields and Markups summary at the end. - Fit to paper, Actual size (100 %) or Custom with a percentage. Tile large sheets cuts a big sheet over several pages with an overlap and crop marks. - Paper: the printer's own, Letter, Tabloid, Arch C, Arch D, Arch E, A4 or A3. - Colour, Grayscale, or Markups in colour, drawing in grayscale. - Print as image at 150, 300 or 600 dpi, for a sheet a printer will not draw as it is. Cella PDF remembers the choices for next time. These are the Mac's options; see Printing.

Sharing. Share offers the PDF, Save a Copy… and the exports (Excel, DXF, PDF/A, flattened PDF). When the trial has ended and no key is entered, the exports are greyed; Share PDF, Save a Copy and Print stay.

Autosave and recovery. Cella PDF saves a copy every two minutes into its own storage, never beside your drawing. If the iPad runs out of power or Cella PDF is closed with changes unsaved, the Home offers Recover unsaved changes… or Discard the next time.

Sheets. In the Sheets pane and in the filmstrip a long press on a sheet opens its menu: Rotate, Move Up, Move Down, Move To…, Delete, Extract, Rename Sheet…, Detect Sheet Numbers…, Crop… and Resize…. Select (in the Sheets pane) picks several sheets to act on at once. The + button inserts a Blank Sheet…, sheets From File… or pictures From Photos…, before or after a sheet. Drag a sheet to reorder; drop a PDF or a picture between sheets to insert it. These are the Mac's page operations with the Mac's confirmations; see Page operations. On an Atrium server that syncs only markups, a sheet change is refused with a note, as on the Mac.

The same menu makes new files from the sheets, and none of them changes the document you have open: - Split Document… cuts the document into several files by Sheet ranges (1-3, 4-6, 7-), Every N sheets, Top-level bookmarks or Sheet-name prefix (A-, S-, M-…), and lists the files it will make as you choose. Name them with File names start with; they go to Files or Share. See Splitting a document. - Export Sheets as Images… saves this sheet, the sheets you chose or all sheets as PNG or JPEG, at 72 to 600 dpi, with or without the markups, one picture per sheet named after the file and the sheet. - Overlay These Sheets (with two to four sheets chosen; Overlay Pages… otherwise) draws the sheets on top of one another, each in its own colour, lined up Automatic or None, with a live preview. The result is inserted as a new sheet (one Undo) or saved as a PDF to Files or Share. See Overlay pages. - Crop… asks what to Apply to: this sheet, the sheets the same size, the sheets you chose or all sheets.

From Photos… (the + button) asks for the Sheet size (the picture's own at its resolution, this sheet's, or a paper with the picture fitted and centred on white), the Orientation, a Resolution for pictures whose file gives none, and where to Insert. Pictures dropped between sheets, and Take Photo's Insert as New Sheet, take the choices you made there last.

Recognize Text (OCR). View ▸ Recognize Text (OCR)… reads scanned sheets on the iPad (nothing leaves it). Choose which sheets: those without text, this sheet or all. You can also write the words into the file as an invisible text layer, and keep the corrections you made before. A progress panel has Cancel, which stops after the sheet in hand. View ▸ Show ▸ Recognized Text shows the words found, so you can check them. With Select, a long press on a word corrects it. Settings ▸ Scanned Sheets reads scanned title blocks for their sheet numbers by itself. The words are kept in the .cella folder beside the file where the folder can be written. Otherwise they are kept in Cella PDF on this iPad only. Search, including Whole Set, uses them. See Search.

The Markups List across a set. With a folder set open (the Set tab), the Markups List's ⋯ menu has Whole Set…, which opens a Whole Set sheet listing every file's markups in one list. It starts with a File column, groups By File (or by subject, status, author, layer or Space), sorts, and has a Filter menu (Status, Author, Type, Measurements Only) and a Filter markups field that look in every file. The Totals line at the foot adds up measurements, each with its own file's scale. Tap a row to open that file at the markup; a long press offers Open “<file>” Here and Set Status…. ⋯ ▸ Export to Excel… and Export CSV… write the list with the File column first. Reading a big set takes a moment ("Reading the set…"); Read the Set Again refreshes it. See The whole set.

Set Status for Selection. In the Whole Set sheet tap Select, tick markups across files (or tap a group's header to tick its markups), then Set Status…. The same command is in the Set menu as Set Status for Selection…. It asks "Set the status of 12 markups in 3 files?" with the status as the answer: Accepted, Rejected, Cancelled, Completed, or None to clear it. It can't be undone: each file is saved with the new status, and the first save in a session keeps the old version as .cella/<file>.bak. Locked markups and ones already at that status are left as they are.

Compare Documents. View ▸ Compare ▸ Compare Documents…, or Compare This File… in the Set menu, compares the open file with another issue of it. Pick the other file in Files, then choose whether it is newer or older, This Sheet or All Matching Sheets, the Sensitivity, the Smallest change, Cloud the changes and their Cloud colour, and whether to Overlay the other issue on the sheet. When the run ends, a Compare button in the bar opens the list of changes. Tap one to go to it, and use Previous and Next to walk through them. Finish leaves the clouds on the sheets (Remove Compare Clouds takes them off). See Compare.

Redaction. Mark what must go with the Redact tool, with Mark for Redaction on selected text, or with Mark Search Results for Redaction in Properties' Redactions menu (Visual Search can mark every symbol it found, too). Apply Redactions… (in Properties, and in Share) removes what lies under the marks for good, on all sheets or this sheet, and can also remove the metadata and the embedded files. By default it writes a new copy, "<file> redacted.pdf", to Files or Share, and leaves the original as it was. Replace the original is offered too, when a backup can be kept and the document isn't synced through Atrium. The backup goes to .cella/<file>.bak beside the file when the folder can be written. When it can't (a PDF opened alone from iCloud Drive or another provider), it goes to On My iPad ▸ Cella PDF ▸ Redaction Backups in Files, as "<file> backup <date and time>.pdf", and the choice names that place. Either way, check the result before you send it. See Redaction.

Signatures. Add Signature… (in the palette's Signatures menu) makes a picture of your signature in one of three ways, as on the Mac. Draw it with the Pencil or a finger (with a small pad for your initials), Type your name in a script face (with its initials), or use an Image: a photo or scan of your signature from Photos or Files, whose paper is made transparent (a slider sets how much). The ink is black or blue. The picture is kept, encrypted, in Cella PDF on this iPad, and the next tap on the sheet places it. A picture of a signature is not a digital signature (below).

Signing with a certificate. Share ▸ Sign Digitally…, or the same item in the palette's Signatures menu, signs the document with a digital signature, so that a reader can tell who signed it and whether it has changed since. It needs a license, or the trial. - Certificate. iPadOS has no list of certificates to choose from, so you bring one. Import Certificate… takes a .p12 or .pfx file from Files and asks for the password it was exported with. The certificate and its private key are kept in this iPad's Keychain, on this iPad only (they don't go to iCloud Keychain), and the password is used once and never kept. One certificate is kept at a time: importing another replaces it, and Remove Certificate… deletes it from the iPad (files already signed stay signed). A certificate that is out of date, or not for signing documents, is refused with a reason. A smart card or a certificate managed by your organisation can't be used; only .p12 and .pfx files can. - Appearance. The signature can sit over the selected signature picture, in a box at the bottom right of this sheet (with a saved signature picture if you choose one), or be invisible. Add Reason, Location and Contact if you like. - Lock the document after signing certifies it with no changes allowed afterwards: any later change shows as invalidating the signature. On a document that already has a signature it locks only the new signature's field. - Sign makes a new copy, "<file> signed.pdf", and offers Save to Files… (then Open Copy), Share… or Discard. Your document stays as it was; changes you hadn't saved are saved to it first, so the copy and the document agree. - Digital Signatures… (in the same menus) lists the signatures in the open document: who signed, when, on which sheet, the reason, and whether the signature is still valid, valid but from a signer this iPad doesn't trust, or not valid. Each is checked against the file as it is on disk. A signature picture is not listed; it is a markup. See Signatures.

Take Photo. Choose Take Photo, then tap the sheet where the photo goes. The camera opens, and the photo lands there as an image markup you can move and resize. A card offers Insert as New Sheet instead, which makes the sheet with the size options of Insert ▸ From Photos…. If the iPad has no camera, or Cella PDF may not use it, you are offered Choose Photo… from your library. Photos are scaled to at most 2048 pixels and, by default, kept without their location or other metadata. Cella PDF asks for the camera the first time. Settings ▸ Take Photo ▸ Keep photo location is off. Turn it on and Cella PDF asks to use the iPad's location while the app is in use. A photo then keeps the place it was taken (a library photo keeps the place its own file records) inside the picture in your file, and nothing else about the camera. Anyone who gets the drawing can read that place, so leave it off unless you want it. It goes nowhere but your file (and your own Atrium server, if you sync).

Reporting a problem. Report a Bug… (in Settings ▸ Help) opens a mail to support. The iPad keeps the last five crash and hang reports that iPadOS gave it, Cella PDF's own record of its last ten crashes (the open documents' names, sizes and counts, memory, and the last commands used, never your drawings), and a log of the times a sheet had to restart, in Cella PDF. After a crash, the next start asks whether to send the report (Send… or Not Now). Nothing is sent by itself. When you report, they go in the mail as a zip, with no drawings or markups, and are deleted once it is sent. Without Mail set up, you are offered Share Diagnostics… (to Files, AirDrop or another mail app), Report Without Them or Delete Diagnostics. Settings ▸ Help ▸ Delete Diagnostics does the last at any time and shows how many reports are kept.

Stamps and overlays. There is no Create Stamp on the iPad: picture and text stamps made on the Mac, Windows or Linux come in with a profile and place as they do there. Overlay Pages works on sheets of the open document, not of other files.

#Appendix: Keyboard shortcuts

Help ▸ Keyboard Shortcuts (⌘/; Ctrl+/) shows this list over the drawing, with a filter field. These are the default keys, the Mac's and Windows and Linux's side by side. Change them in Settings ▸ Keyboard on every platform (on the Mac, Cella PDF ▸ Settings… ▸ Shortcuts…); the list then shows yours. Single-key tool shortcuts work while the drawing has the keyboard, never while you type in a field. Once the free trial has ended, only Select and Pan work until you buy Cella PDF.

#Navigation

#View

#Tools

#Markup

#Sheets

#Edit

#Panels

#File

#App and Window