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

    The optional Profile argument specifies a string of information
    that can be used when the HDLC protocol is dependent on network
    subscription time commitments pertinent to the Data Link layer.
    When specified, the values of some link characteristics may be
    overridden. This argument determines the value of the profile
    characteristic. The default value of this argument is a null
    string, meaning that no profile is used.