Represents the "JS" entry of the rendition action object.

It is defined as part of the PDF 1.0 specification.

This property may contain one of two different types:.

1) A string representing a PDF string object.

2) A StreamElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 214, page 428.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 218, page 521.