grammar Grammar {
    token TOP { <chunk>+ }

    token chunk {
        || <text>
        || <subnegotiation>
        || <negotiation>
        || <command: NOP..GA>
    }

    # All bytes passed are encoded as latin1.
    token byte { . }

    # TELNET data is ASCII encoded. xtended ASCII is supported, but characters
    # outside the normal ASCII range are sent as XASCII subnegotiations.
    token text { <:ascii>+ }

    token command($guard) {
        \x[FF]
        <( <[ \x[F0]..\x[FE] ]> )>
        <?{ ~$/ ~~ $guard }>
    }

    token negotiation {
        <command: WILL..DONT>
        <option=.byte>
    }

    proto token subnegotiation {*}
    token subnegotiation:sym(NAWS) {
        <command: SB>
        <option=.sym>
        <byte> ** 4
        <command: SE>
    }
}