Every change found, including the ones nobody circled
A revision cloud is a promise: this is what changed. On a busy project that promise is broken constantly — not maliciously, just because a designer moved a wall at 11pm and forgot to cloud it.
The site does not find out from the drawing. It finds out when the blockwork does not fit, or when a slab is poured over a shaft that was supposed to have an opening. By then the cost is a core cut, not a pencil line.
So the agent compares the geometry itself. Five changes on this sheet; the designer clouded three. The two nobody circled are the two that cost money.
Nothing on this screen is posted, paid or sent by the machine. It produces a document with its sources attached, and a person presses the button.
A revision letter is not a version. Sheets get reissued under an unchanged revision number all the time, and nothing in a normal drawing register notices. Every upload is hashed and compared against what was received before — same sheet, same revision, different content is a finding.