Represents the "X" entry of the rectilinear measure dictionary object.

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

It contains an array which contains NumberFormatElements.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 262, page 481.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 267, page 594.

The X array contains one or more number format dictionaries specifying how x-axis coordinates are converted and displayed. Multiple entries allow compound unit expressions such as feet and inches.