A transport extension is one which is primarily used in inter-
    server communications. Following are the descriptions of each
    transport extension commands and the responses which will be
    returned by those commands.

    Each command is shown in upper case for clarity, although
    case is ignored in the interpretation of commands by the
    NNTP server.  Any parameters are shown in lower case.  A
    parameter shown in [square brackets] is optional.  For
    example, [GMT] indicates that the triglyph GMT may present
    or omitted. A parameter that may be repeated is followed
    by an ellipsis.