This issue was originally reported by Dave Peterson.

The year 0000 should be allowed in the types date, dateTime, gYear and
gYearMonth.

In the 1998 version of ISO 8601 the year 0000 was prohibited.  This
was changed in the 2000 version.  We have received mail from James
Clark and others that this should be corrected.

See (member-only link)
http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2002Oct/0258.html
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2002Oct/0258.html).

Approved for addition in Chapel Hill:
http://www.w3.org/XML/2002/10/xml-schema-ftf-minutes#xs11.3111
(http://www.w3.org/XML/2002/10/xml-schema-ftf-minutes#xs11.3111).

This may have been solved by accepting the erratum for R-120
(member-only link)
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2002Oct/att-0363/00-part)
which includes a note about allowing year 0000.

This item was mentioned in the meeting of 2003-09-18
(http://www.w3.org/XML/Group/2003/09/xml-schema-ftf-minutes.html)

Proposal:

Dave Peterson erratum for R-120 (member-only link)
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2002Oct/att-0363/00-part)

This requirement has been met; XML Schema 1.1 allows '0000' as a
lexical representation of 1 BCE, and documents the meaning of
literals with a preceding minus sign in the corresponding way:
-0001 is 2 BCE, etc.