I'm just going through my Noda Time <http://nodatime.org> code for time zone handling, and I've noticed I'm being even more defensive than normal, by handling the situation where a time zone transition is specified to occur on the 29th of February - I skip forward or backwards to the nearest leap year. This feels like it's overkill to me, and that it would be better just to prohibit this situation from occurring in my code, *if* it's widely accepted to be invalid data. Is there anything specifying the behaviour if such data is presented? I could try running the zoneinfo compiler myself, but I suspect it would take a long time to get all the tools sorted, and I wouldn't be certain of interpreting the outcome properly. If anyone just *knows,* that would save me a lot of effort :) Jon