Standard XML format – http://www.w3.org/TR/xmlschema-2/#dateTime :
188.8.131.52 Lexical representation
The ·lexical space· of dateTime consists of finite-length sequences of characters of the form: ‘-‘? yyyy ‘-‘ mm ‘-‘ dd ‘T’ hh ‘:’ mm ‘:’ ss (‘.’ s+)? (zzzzzz)?, where
- ‘-‘? yyyy is a four-or-more digit optionally negative-signed numeral that represents the year; if more than four digits, leading zeros are prohibited, and ‘0000’ is prohibited (see the Note above (§3.2.7); also note that a plus sign is not permitted);
- the remaining ‘-‘s are separators between parts of the date portion;
- the first mm is a two-digit numeral that represents the month;
- dd is a two-digit numeral that represents the day;
- ‘T’ is a separator indicating that time-of-day follows;
- hh is a two-digit numeral that represents the hour; ’24’ is permitted if the minutes and seconds represented are zero, and the dateTime value so represented is the first instant of the following day (the hour property of a dateTime object in the ·value space· cannot have a value greater than 23);
- ‘:’ is a separator between parts of the time-of-day portion;
- the second mm is a two-digit numeral that represents the minute;
- ss is a two-integer-digit numeral that represents the whole seconds;
- ‘.’ s+ (if present) represents the fractional seconds;
- zzzzzz (if present) represents the timezone (as described below).
For example, 2002-10-10T12:00:00-05:00 (noon on 10 October 2002, Central Daylight Savings Time as well as Eastern Standard Time in the U.S.) is 2002-10-10T17:00:00Z, five hours later than 2002-10-10T12:00:00Z.