This class represents the hide action. This is definitively detailed in:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 210, page 426.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 214, page 518.

System.Object
    WebSupergoo.ABCpdf14.Elements.Element
       WebSupergoo.ABCpdf14.Elements.ActionElement
          WebSupergoo.ABCpdf14.Elements.HideActionElement

A hide action shows or hides one or more annotations by setting or clearing their Hidden flag. The T entry identifies the targets - a single reference, an array of references, or a field name string - and H selects whether to hide or show.