VMS Help DECnet-Plus, DCL Commands, SET, HOST, /MOP, Qualifiers, /DISCONNECT=disconnect-character  *Conan The Librarian (sorry for the slow response - running on an old VAX)

     Specifies the character which is to be recognized as a request
     to terminate the connection with the remote system.  Once the
     connection is established, pressing the Ctrl key and this
     character terminates the connection. The default character is ].