XML Tutorial/XML Schema/recurringDate

When the year doesn"t matter, but the month and day do, use xsd:recurringDate

File: Schema.xsd
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  targetNamespace="http://www.wbex.ru" 
  xmlns="http://www.wbex.ru"
  elementFormDefault="qualified">
  <xs:element name="birthday" type="xs:recurringDate" />
</xs:schema>

File: Data.xml
<?xml version="1.0"?>
<birthday>--03-14</birthday>