The changes a certification signature permits after it (the P entry of the DocMDP transform parameters), or a signature
field lock permits after its signature (the lock's P, PDF 2.0).
[SuppressMessage("Design", "CA1008:Enums should have zero value", Justification = "The values are the numbers the P entry holds; 0 is not one of them.")]
public enum PdfCertificationPermissions
ISO 32000-2 §12.8.2.2, Table 257, and §12.7.5.5, Table 236. Whatever the value, incremental updates that only add a document security store (§12.8.4.3) or a document timestamp (§12.8.5) are not changes to the document.
kind:method, kind:property, kind:ctor. Press Esc to clear.FormFilling2: filling in forms, instantiating page templates and signing; other changes invalidate the signature. The default.FormFillingAndAnnotations3: what FormFilling permits, and creating, deleting and modifying annotations.NoChanges1: no changes; any change invalidates the signature.