XML Tutorial/XML Schema/year

The day and month are not known, and so it makes sense to have an element that only requires the year

<?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="last_seen" type="xs:year" />
</xs:schema>

File: Data.xml
<?xml version="1.0"?>
<last_seen>1950</last_seen>