Represents the "W" entry of the cross-reference stream dictionary object.

It is a required entry defined as part of the PDF 1.0 specification.

It contains an array which contains integers, representing PDF numeric objects.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 17, page 50.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 17, page 66.