Schema for description section of Identify reply of OAI-PMH v2.0.
For repositories that comply with the oai format for unique identifiers
for items records.
See: http://www.openarchives.org/OAI/2.0/guidelines-oai-identifier.htm
Validated with http://www.w3.org/2001/03/webdata/xsv on 2002-05-16
Corrected to handle single letter elements in domain name, e.g ebibpol.p.lodz.pl 2007-05-22
Simeon Warner $Date: 2007-06-07 19:28:11 $