There is another, but in my opinion, more complicated, method involving ECN (Encoding Control Notation). With ECN, you could specify that ENUMERATED types are always encoded as unsigned values.
BTW information about ECN can be found at http://asn1.elibel.tm.fr/ecn -- Olivier DUBUISSON france telecom R&D
DTL/TAL - 22307 Lannion Cedex - France t: +33 2 96 05 38 50 - f: +33 2 96 05 39 45 - http://asn1.elibel.tm.fr/
