VMS Help PRODUCT, PACKAGE, Qualifiers, /SOURCE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SOURCE=file-specification

    Specifies the location of the input PDF file. If the device name
    is omitted, it defaults to the user's default device. If the
    directory name is omitted, it defaults to the user's default
    directory. If the file name and file type components of the file
    specification are not provided, they default to <full-product-
    name>.PCSI$DESCRIPTION.

    The optional PTF file, if used, must be in the same directory and
    have the same file name as the PDF with a .PCSI$TEXT file type.
    If a file named <full-product-name>.PCSI$TEXT is not found, the
    package operation does not use a PTF file.

    This is a required qualifier for the PRODUCT PACKAGE command. The
    logical name PCSI$SOURCE is not used.