I hope that everyone has recovered from Thanksgiving by now :-) and that you're ready to think about representations of time again. I know it's very late to suggest something like this -- probably too late for the ISO committee to consider, even if all of us love it -- but I think it's worth recording this for the future regardless.
It seems to me that many of the difficulties we've been discussing essentially result from allowing multiple formats, especially very short formats -- and especially for decades, centuries, etc. Why allow, e.g., "19" to represent the 1900s (or possibly the 20th century? I forget), with attendant confusion about how to represent the year 19 C.E., when we already allow "19XX" (or some such; I'm not sure what current thinking is about the last two chars.)? This seems so obvious to me I wonder if I'm missing something?
Along the same lines, in 2004, 8601's Basic format might have been a good idea; now that disk space is incredibly cheap and bandwidth is orders of magnitude cheaper than in 2004, I think it'd make sense to deprecate and eventually drop Basic format and require Extended format. We're likely to want to represent more and more complex temporal information, and maintaining compatibility with very short formats is likely to be a bigger and bigger albatross around our necks as time goes on.
What am I missing?
Woodrow Wilson Indiana Teaching Fellow
Adjunct Associate Professor of Informatics
Visiting Scientist, Research Technologies
Indiana University Bloomington