VMS Help DECTPU, TPU$TPU, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 command

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor
    Command string. Note that the verb is TPU instead of EDIT/TPU.
    The command argument is the address for a descriptor of a command
    line.