/sys$common/syshlp/helplib.hlb LANCP, CONNECT, NODE, Qualifiers, /DISCONNECT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /DISCONNECT=disconnect-character

    Specifies a character that you can use to terminate the
    connection to the remote node. To terminate a connection, press
    Ctrl/disconnect-character. You can select any ASCII character
    from @ through Z, except C, M, Q, S, Y; the default disconnect
    character is D.