source-string

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor

    Source string. The source-string argument is the address of a
    descriptor pointing to the source string. The descriptor class
    can be unspecified, fixed length, dynamic, scalar decimal, array,
    noncontiguous array, or varying.

 destination-string

    OpenVMS usage:char_string
    type:         character string
    access:       write only
    mechanism:    by descriptor

    Destination string. The destination-string argument is the
    address of a descriptor pointing to the destination string. The
    class field determines the appropriate action.