Library /sys$common/syshlp/nclhelp.hlb create, frame (OpenVMS), link, control_mode  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The optional Control Mode argument specifies the mode in which
    the link operates.  This argument determines the value of the
    control mode characteristic.  The default is point-to-point.
    Possible mode values are:  multipoint master, multipoint
    tributary, and point-to-point.