Evidence.
How Send NDA records what was signed, by whom and when, and how anyone can check a copy later.
03
Evidence
3 articles
The signing record
The chained log of every step, and what each entry holds.
The sealed PDF
How a completed agreement is frozen, what its signing certificate holds, and why a later change cannot reach either.
Verify a copy
Upload a PDF and see whether it is, byte for byte, the one both parties signed, or its signing certificate.