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

 o  device constraint

    The value of an attribute is not supported by the type of device
    used on the communications line. Modify the attribute to a
    suitable value, and retry the operation.

 o  open physical port failed

    The opening of the port in the Physical layer failed. The
    exception includes an argument that gives more information about
    the failure.