XML Schema Reference

The XML Schema Complete Reference Errata

• p.307--The Use of year '0000' is prohibited. Note that this is in conflict with ISO 8601, which permits year 0 references. We anticipated a change that didn't happen in the Schema 1.0 Reccommendation; it is expected to change with the Schema 1.1 Recommendation to be in harmony with ISO 8601:2000. WARNING: If you use negative-year dates/dateTimes/etc. with Schema 1.0 processors, expect their interpretation to change when seen by processors adhering to future revisions of the Recommendation.
• XML Schema date types are based on the Gregorian calendar, period. Even for dates that occurred long before the invention of the Gregorian calendar. The earlier ("Julian") calendar never is used. This means that what people long ago considered the date to be on a particular day is not what we—today—generally consider the date of that day to be. So, in particular, there is no year with a very short "correcting" month.