; be able to handle padding
                       ; added by message transports.

  tspecials :=  "(" / ")" / "<" / ">" / "@" /
                "," / ";" / ":" / "\" / <">
                "/" / "[" / "]" / "?" / "="
                ; Must be in quoted-string,
                ; to use within parameter values

  type := discrete-type / composite-type

  value := token / quoted-string

  version := "MIME-Version" ":" 1*DIGIT "." 1*DIGIT

  x-token := <The two characters "X-" or "x-" followed, with
              no  intervening white space, by any token>