Represents the "Ysquare" entry of the type 10 halftone dictionary object.

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

It contains an integer representing a PDF numeric object.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 132, page 313.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 130, page 375.