Note that the ASN.1 GeneralizedTime type (UNIVERSAL 24) already dseems to do
what we want; it contains the date (4 digit year), followed by the time to
any precision allowed by ISO 3307 (including, I believe, hours, minutes,
seconds, or fractions of seconds).
Changing the definition of a certificate in X.509 to have a
CHOICE { UTCTime, GeneralizedTime} rather than UTCTime would allow 4 digit
years while retaining compatability with old certificates.
I would imagine that it's far too late now to get this into X.509(92).
However, it could be raised as yet another issue to be considered as part of the
certificate New Work Item (JTC1 N1475 or its descendants).
Given the usual speed of the standarization process, we will be lucky if this
is fixed by the time the year wraps round in 2000...
Mike