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 environment name VAXC$PATH.

 argv

    An array of pointers to null-terminated character strings.
    These strings constitute the argument list available to the new
    process. By convention, argv[0] must point to a string that is
    the same as the new process filename (or its last component).
    argv is terminated by a NULL pointer.