error in spec for xs:date

Hi,

I noticed a contradiction in the spec in section “3.2.9 date”. The  
spec reads “… the first moment of 2002-10-10+13:00 is  
2002-10-10T00:00:00+13, which is 2002-10-09T11:00:00Z…”

This sentence implies that to get the UTC equivalent first moment of  
“2002-10-10+13”, the equation is 2002-10-10T00:00:00Z – 13:00 =  
2002-10-09T11:00:00Z (or the formula is midnight of that date in UTC  
– hours offset = first moment in UTC).

However, later on in that section we have “For example,  
2002-10-10-05:00 begins during 2002-10-09Z…” This is a contradiction,  
because according to the above formula, we would have  
2002-10-10T00:00:00Z – (-05:00) = 2002-10-10T05:00:00Z. Thus,  
2002-10-10-05:00 would begin actually on 2002-10-10Z. Hence the  
contradiction. So which is correct and what is the correct formula to  
calculate when the first moment is in UTC, given a timezone offsetted  
xs:date?

Thanks,
-Andrew