xs:gMonth
The xs:gMonth type represents a certain month of the year in the
Gregorian calendar as an integer between --01 and --12. An optional time zone suffix in
the form hh:mm or Z to indicate Coordinated Universal Time
(UTC) can be added as well. These are all valid xs:gMonth values:
--01
--12
--12Z
--09+02:00
--03-11:00
The original release of XML Schema Part 2: Datatypes had a
mistake here. It specified extra hyphens after the month part;
for instance, --01-- and
--12--. Some schema
processors still allow or require this format.
The g indicates that the month is given
using the Gregorian calendar. Schema date types are not
localizable to non-Gregorian calendars. If you need a different
calendar, you'll need to derive from xs:string using the pattern facet.
Constraining facets that apply to xs:gMonth are minInclusive, maxInclusive, minExclusive, maxExclusive, pattern, enumeration, and whiteSpace. However, if the time zones
are not specified, it may not be possible to determine
conclusively whether one month starts before another. If time
zones are specified, months are compared by their first moment.
Thus, --12-05:00 is greater
than --12-Z, which is greater
than --12+02:00.