I user has requested API access to a PDF documents page label attribute in the catalogue. The Page labels stores a number tree representing the page label format for a given range of page numbers. The spec has more information on this but the format can be broken down in to the following types.

S name(Optional) The numbering style to be used for the numeric portion of each page label:
     D - Decimal arabic numerals
     R - Uppercase roman numerals
     r - Lowercase roman numerals
     A - Uppercase letters (A to Z for the first 26 pages, AA to ZZ for the next 26, and so on)
     a - Lowercase letters (a to z for the first 26 pages, aa to zz for the next 26, and so on)

There is no default numbering style; if no S entry is present, page labels consist solely of a label prefix with no numeric portion. For example, if the P entry (below) specifies the label prefix Contents, each page is simply labeled Contents with no page number. (If the is also missing or empty, the page label is an empty string.)

P text string(Optional) The label prefix for page labels in this range.

St integer(Optional) The value of the numeric portion for the first page label in the range. Sub-
sequent pages are numbered sequentially from this value, which must be greater than or
equal to 1. Default value: 1.