/sys$common/syshlp/helplib.hlb RTL Routines, STR$, STR$PREFIX, Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 destination-string

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

    Destination string (dynamic or varying length). STR$PREFIX copies
    the source string into the beginning of this destination string.
    The destination-string argument is the address of a descriptor
    pointing to the destination string.

 source-string

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

    Source string that STR$PREFIX copies into the beginning of the
    destination string. The source-string argument is the address of
    a descriptor pointing to the source string.