file_name

    The filename of a new image to be activated in the child process.
    The device and directory specification for the file is obtained
    by searching the VAXC$PATH environment name.

 argn

    A sequence of pointers to null-terminated character strings. By
    convention, at least one argument must be present and must point
    to a string that is the same as the new process filename (or its
    last component).

  . . .

    A sequence of pointers to strings. At least one pointer must
    exist to terminate the list. This pointer must be the NULL
    pointer.