Library /sys$common/syshlp/net$mgmt_help.hlb session_trans, status  *Conan The Librarian (sorry for the slow response - running on an old VAX)

   PROTOCOL

       Transport protocol used by this transport service, as specified by the
       user when this service was created. See the create command description
       for a list of possible values.

   TSEL

       Transport selector used by the OSI Transport Module to bind incoming
       connection requests to Session Control.  This attribute is not
       applicable for NSP transport.