Represents the "TimeStamp" entry of the signature field seed value dictionary object.

It is an optional entry defined as part of the PDF 1.6 specification.

It contains a SignatureFieldTimeStampElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 234, page 448.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 8.83, page 44.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 237, page 543.