PDF glossary
Incremental update
Saving changes to a PDF by appending them to the end of the file, so the original bytes — and any signature over them — stay intact.
A PDF can be saved by rewriting it, or by adding a new section at the end that records what changed. The second way leaves every earlier byte exactly where it was.
This is how a document can carry several signatures: each new one is appended, and the earlier ones still cover the bytes they signed.
In PDF-SDK
Signing appends to the file, so earlier signatures stay valid and a second person can counter-sign.
PDF signaturesLast reviewed