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

 message-string

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

    Message string written to the current controlling output device
    by LIB$PUT_OUTPUT. The message-string argument is the address
    of a descriptor pointing to this message string. RMS handles all
    formatting, so the message does not need to include such ASCII
    formatting instructions as carriage return (CR).