This class represents the signature field lock dictionary. This is definitively detailed in:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 233, page 447.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 236, page 541.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 8.82, page 43.

This class is always an indirect object because SignatureFieldElement.EntryLock requires it to be so.

System.Object
    WebSupergoo.ABCpdf14.Elements.Element
       WebSupergoo.ABCpdf14.Elements.SignatureFieldLockElement

A signature field lock dictionary specifies which fields should be locked when the associated signature field is signed, evaluated at signing time.

The Action entry selects the policy: All (lock all fields), Include (lock only the listed fields), or Exclude (lock all fields except the listed ones). The Fields array names the included or excluded fields.