> ## Documentation Index
> Fetch the complete documentation index at: https://docs.elevatedsignals.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Apply an electronic signature

> How signing works and what gets recorded.

Controlled transitions (approvals, closures, effectiveness verification) require an electronic
signature. When you sign, Invariant captures:

* **Signer identity** and a re-verification of your credential at the point of signing
* **Timestamp** and the **meaning** of the signature
* The **exact content/version** being signed (the signature is bound to a content digest)
* A linked, hash-chained audit entry

Signature records are append-only. See [21 CFR Part 11 / Annex 11](/invariant/compliance/part-11-annex-11).