Represents the "CMD" entry of the rich-media-execute action object.

It is a required entry defined as part of the PDF 1.7 Extension Level 3 specification.

It contains a RichMediaCommandElement.

For definitive details see:.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 8.48a, page 40.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 222, page 523.