What changed between two issues.

Comparing revisions

Save a revision when a drawing set is issued. Blueprint Auditor keeps the quantities that set produced and a fingerprint of every sheet in it, and can then answer two different questions about the next issue.

Getting the next issue into the same project

A comparison reads two revisions of one project, so the revised set has to land in the project it revises rather than beside it. Upload it the way you upload anything, and on Save choose a new issue of a project you already have.

The quantities that project already measured are kept as a revision before the new ones replace them, so the first comparison is available immediately. The drawings themselves are replaced, not added to — one project holds one set. Marks and pins stay where they are on the sheet, and if any of them sit on a page the new issue does not have, the program says how many rather than deleting them.

Quantity change

What the takeoff measured then, against what it measures now: quantities that went up, quantities that went down, and the ones that did not move. Where the project has been sent to AI Estimator, the added scope can be priced into that same estimate and staged as a pending change order for the movement in its bid.

Removed quantities are shown and never priced automatically. A quantity that disappeared is a credit somebody has to negotiate, not an arithmetic result.

Sheet comparison

The question a reviewer asks first, holding an addendum, is which sheets to open. The sheet comparison answers it: sheets added, sheets withdrawn, and sheets that changed, with the kind of change named — the words changed, the line work moved, or it was re-issued at a different paper size.

Sheets are matched by the number in their title block, so a sheet that moved position in the set is still that sheet. Where a set has no readable numbers, sheets are matched by position, and the result says so: inserting a sheet in the middle then makes the ones after it look changed.

What it does not tell you

• It names the kind of change on a sheet, never the change itself. "A2.3 has a new door" would be a guess, and you are opening the sheet either way.
• A revision saved before sheets were recorded has no fingerprints to compare. Save a revision of each issue and compare those.
• A revision holds quantities and fingerprints, not a second copy of the drawings. It is a record of what a set produced, not an archive of the set.