SpotBit — find every changed sheet since the last issue

SpotBit compares your drawing with its previous version and lists every layout that shows a change, then sends just those sheets to Publish. No more flipping through dozens of sheets before a reissue.

How SpotBit works

You point SpotBit at the version you issued last time. It finds what changed since then and tells you which sheets show it.

1. Compare

Select the previous version of your drawing. SpotBit reads it in the background and compares it with the drawing as it is open now, unsaved changes included.

2. SpotBit detects

Everything that changes what you see on a sheet: added, changed and deleted objects, new, changed or removed viewports, layers switched on, off or restyled, and changes on the sheet itself (title block, notes).

3. Review & publish

The dialog lists the affected layouts in tab order. Copy the list, or publish exactly those sheets with their own page setups.

Setup

SpotBit consists of two files and has no settings. One habit makes it work: keep the version you issued.

Keep both files together

Place SpotBit.lsp and SpotBit.dcl in the same folder, and add that folder to the AutoCAD Support File Search Path (OPTIONS → Files).

Load the tool

Load SpotBit.lsp with APPLOAD. Add it to the Startup Suite to have it in every drawing. The command line confirms: “SpotBit loaded. Type SPOTBIT or SV to start.”

Keep the issued version

Each time you issue plans, save a copy of the drawing, e.g. project_2026-10-15_issued.dwg. That copy is what you compare with at the next revision.

Download both files

SpotBit.lspThe tool itself SpotBit.dclThe dialog

Good to know: SpotBit changes nothing in your drawing. It only writes a sheet list file (*_SpotBit.dsd) next to the drawing when you publish. With the AutoCAD Express Tools installed, a progress bar in the status bar shows how far the comparison is.

The SpotBit dialog

Type SPOTBIT or SV to open. It reads from top to bottom: compare, review, act.

SpotBit — CompanionBits SnipBit

What this does

Compares this DWG with a previous version and finds every layout that shows a change.

How to use

1. Click ‘Compare with previous’ and select the older version of this DWG
2. Review the list; copy it, or publish the affected layouts

Compare with previous...

Affected layouts

Ground floorsheet1 changed

Ground floorviewport3 changed, 1 added

Site planviewportview changed

Section A-Aviewport2 deleted

6 model space change(s), 1 sheet(s) changed - 3 layout(s) affected. Click a line for details.

Details of the selected line

added - line (WALLS)

changed - dimension (DIM) - value

2x changed - polyline (WALLS) - moved/reshaped

Publish affected layouts...Copy to clipboardClose

After comparing with the issued version

01Compare with previous...

Opens a file dialog to select the previous version. The comparison runs in eight steps, shown in the status bar. The dialog then reopens with the results. Compare again any time, for example with another version.

02Affected layouts

One line for the sheet itself and one per viewport that shows a change, in the order of your layout tabs. See Results for what each line means.

03Details

Click a line in the list to see what exactly changed there: which objects, on which layer, and what happened to them (moved, other text, other layer, an attribute value, a dynamic property, a layer switched off…). Identical changes are counted (3x …).

04Status line

Sums up the result: how many changes, how many layouts are affected, or a warning when the two drawings don't share their history.

05Publish affected layouts...

Writes a sheet list with only the affected layouts, saves the drawing and opens AutoCAD's Publish dialog. Each layout keeps its own page setup.

06Copy to clipboard

Copies the list as tab-separated text, with the details of each line below it. Paste it into an e-mail, a document or straight into Excel columns.

Workflows

From “what changed?” to the printed revision set.

You issued the plans last month. Since then you moved walls, edited dimensions and updated the title block. Before reissuing, you want every sheet that shows a change.

01Open the current drawing. Type SV.
02Click Compare with previous... and select the copy you saved when you issued last time.
03Watch the progress in the status bar. For a large drawing this takes a few seconds.
04The list shows every affected layout: changes in model space through its viewports, changed viewports, and changes on the sheet itself.

Tip: you don't need to save before comparing. SpotBit compares the drawing as it is open now, including changes you haven't saved yet.

Straight from the result list to PDF or printer, with each sheet's own page setup.

01After comparing, click Publish affected layouts...
02A small dialog shows how many layouts are in the sheet list and where it was saved. Click Save and Publish. SpotBit saves your drawing, so all your changes end up on the plots.
03AutoCAD's Publish dialog opens. Click Load Sheet List (the folder icon) and select the *_SpotBit.dsd file next to your drawing.
04Only the affected layouts are now in the list, in tab order. Choose your output (for example one multi-sheet PDF) and click Publish.

Why the extra click? AutoCAD offers no way to open the Publish dialog with a list already filled in. Loading the sheet list yourself keeps all Publish options available: output type, sheet order, or leaving out a sheet.

Tip: a layout that is affected both on the sheet and in a viewport appears twice in SpotBit's list, but only once in the sheet list.

Turn the result into a list for a transmittal, an e-mail to the contractor or your own checklist.

01Compare as usual.
02Click Copy to clipboard. The status line confirms.
03Paste into Excel: layout, sheet/viewport and changes land in separate columns. In an e-mail or document, each line stays one line.

Note: the same list is also written to the command line. If copying ever fails, press F2 and copy it from the text window.

SpotBit needs the version you want to compare with as a separate file. If you always save over the same file, that version is gone.

01When you issue plans, save a copy with a date or index in its name.
02Keep working in your normal drawing.
03At the next revision, compare with that copy.

Don't rely on the .bak file. It holds the previous save, not the previous issue. After a few saves you would compare with an in-between version and miss changes.

Important: the copy must come from the same drawing (Save As or a file copy). SpotBit matches objects by their internal handle. A drawing rebuilt with WBLOCK or copy-paste into a new file does not share that history; SpotBit then warns you instead of showing a wrong result.

Some object types store data that AutoCAD recalculates when a drawing is opened. SpotBit already ignores the known cases, but a new one can always show up.

01Compare the drawing with an unchanged copy of itself. SpotBit should report no changes.
02If it does, type SVDIAG and select the same copy.
03Press F2, copy the output and send it to us. It shows exactly which object types and properties differ.

Not a false alarm: an edited dynamic block often shows up as one deleted and one added. AutoCAD replaced it with a new object; the sheets SpotBit lists are still the right ones.

What the results mean

Each line is a sheet or a viewport on a layout. Three columns, tab-separated. Click a line for the details.

Column	Example	Meaning
Layout	Ground floor	The layout tab. Lines follow your tab order.
Where	sheet · viewport · viewport 2 · viewport (clipped)	sheet: something on the paper sheet itself changed. viewport: a change visible through a viewport. Viewports are numbered only when a layout has more than one affected viewport. (clipped) marks a non-rectangular viewport; check that one yourself.
What	3 changed, 1 added	The number of changed, added and deleted objects in that sheet or viewport. Click the line to see the details below the list.

Term	Meaning
changed	The object exists in both versions but is different: moved, resized, other text, other layer, other attribute value… A moved object counts where it was and where it is now.
added	The object only exists in the current drawing.
deleted	The object only exists in the previous version. SpotBit uses its old position to find the viewports.
view changed	The viewport itself was changed: moved or resized on the sheet, panned, rescaled, twisted, or layers frozen or thawed in it.
new	The viewport did not exist in the previous version.
layer changed: WALLS	The layer itself changed between the two versions: switched on or off, frozen or thawed, set to plot or not, or another colour, linetype, lineweight or transparency. Every sheet and viewport showing objects on that layer is listed, also when you switched it off, because then something disappeared from the sheet.
viewport removed	A viewport that was on this layout in the previous version is gone.
new layout	The whole layout is new. A renamed layout is still recognised as the same layout.
1 deleted, 1 added	Often one edited object that AutoCAD replaced by a new one, for example a dynamic block after certain edits, RESETBLOCK or a replaced block. The object gets a new internal handle, so SpotBit sees the old one as deleted and the new one as added. The right sheets are still found; only the label differs.

In the details	Means
moved/reshaped	Position or shape changed (coordinates, vertices, hatch boundary…)
text	Other text in a text, mtext or table cell
attribute DATE	The value of that block attribute changed, typically the title block
value / text override	A dimension measures something else, or its text was overridden
dynamic property	A dynamic block got another length, flip, visibility state…
layer, colour, linetype, lineweight	The object's own properties changed
block definition	The block itself was edited; this insert didn't move
layer WALLS - switched off	What happened to a changed layer: switched on/off, frozen/thawed, colour, linetype…
viewport - panned, scale/zoom	What happened to a changed viewport: moved on sheet, resized, panned, scale, twist, layers frozen/thawed in it

Limitations

SpotBit is an aid, not a guarantee. These are the cases worth knowing.

SpotBit shows the sheets you changed, not the sheets you should have changed. Move a wall on the floor plan and forget to update the elevation: the elevation is now wrong, but nothing on it changed, so SpotBit won't list it. Keeping plans, sections and elevations consistent is still your job. Use SpotBit to narrow down your check, not to replace it.

Case	Behaviour	Workaround
Block definition edited	Supported: every insert of that block counts, nested blocks included	—
Title block changes	Supported: a changed title block definition marks every layout that uses it	—
Attributes, tables	Supported: compared on what you see	—
Edited dynamic blocks	Found, but often reported as 1 deleted, 1 added instead of changed, because AutoCAD replaces the block reference	Read it as one changed block: the affected sheets are correct
Fields (layout name, date, file name, sheet number…)	Compared on the field itself, not on the value it shows: a field that only shows another value (e.g. a new date) is not reported	—
Annotative objects	Supported, independent of the current annotation scale	—
Hidden layers	Only what is visible on the sheets counts. Changes on layers that are off, frozen (globally or in that viewport), set to Plot = No, or Defpoints are ignored	—
Layer switched on/off, frozen/thawed, restyled	Detected, including a layer you forgot to switch back on. Reported as layer changed	—
Colour/linetype overrides per viewport	Not compared	Use StateSync to keep viewport layers under control
Twisted viewports, layouts never opened	Supported	—
Pressing ESC during a comparison	Stops cleanly: the progress bar closes and the previous version is released	—
Drawing without shared history	After WBLOCK or copying into a new drawing, objects don't match: SpotBit shows a warning	Always keep copies made with Save As or a file copy
Xrefs	Not compared: changes inside an xref are not found	Check sheets showing a changed xref yourself
Page setups	Not compared (printer, paper size, plot style)	—
Clipped (non-rectangular) viewports	Tested against the rectangle around the clip: a change just outside the clip shape can still be listed. These lines are marked (clipped)	Check those viewports visually
Objects near a viewport edge	SpotBit tests the rectangle around each changed object. A long or diagonal object just outside a viewport can still list it, on purpose: one sheet too many is better than one too few	—
Viewports that are switched off	Still listed	Check the viewport's On/Off state
Perspective views	Not supported: results are unreliable	—
Publish	Needs a drawing saved on disk at least once; the Publish dialog does not load the sheet list by itself	Click Load Sheet List in the Publish dialog
AutoCAD LT	Supported (LT 2024 and later). LT can't read drawings in the background, so SpotBit briefly opens the previous version read-only and closes it again	—

Part of CompanionBits

SpotBit is part of the CompanionBits suite for AutoCAD. Every tool solves one problem, completely.

Ready to plot just those three changed sheets instead of all eighty?

Free, no account needed. Download both files, keep them in the same folder and load SpotBit.lsp with APPLOAD.

SpotBit.lsp SpotBit.dcl