VMS Help CONVERT, /DOCUMENT, CDA Base Service Converters, PostScript Output Converter, PAPER_WIDTH  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    PAPER_WIDTH value specifies a paper size other than one of the
    predefined sizes provided. The default paper width is 8.5 inches
    (in). Other valid units of measurement are: centimeters (cm),
    millimeters (mm), and points (pt or po).