This class represents the collection sort dictionary. This is definitively detailed in:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 158, page 373.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 156, page 449.

System.Object
    WebSupergoo.ABCpdf14.Elements.Element
       WebSupergoo.ABCpdf14.Elements.CollectionSortElement

A collection sort dictionary specifies the default sort order for files displayed in a portfolio. The S entry names the schema field to sort by, and A selects ascending or descending order.

Both S and A may be arrays of equal length to specify a multi-level sort: the viewer applies the first sort key first, then uses subsequent keys to break ties.