Library /sys$common/syshlp/nclhelp.hlb set, x25_access, reachable_address, dte_class  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: No class      Value: Class name
    name

    Name of the DTE class to be used in making the outgoing call. If
    not specified, any DTE class may be used.

    Example:

    set x25 access reachable address FRED dte class remote-class-0