VMS Help RTL Routines, STR$, STR$CONCAT, 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 into which STR$CONCAT concatenates all
    specified source strings. The destination-string argument is
    the address of a descriptor pointing to this destination string.

 source-string

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

    First source string; STR$CONCAT requires at least one source
    string. The source-string argument is the address of a descriptor
    pointing to the first source string. The maximum number of source
    strings that STR$CONCAT allows is 254.

 source-string

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

    Additional source strings; STR$CONCAT requires at least one
    source string. The source-string argument is the address of a
    descriptor pointing to the additional source string. The maximum
    number of source strings that STR$CONCAT allows is 254.