The following example is a datatype definition for a user-derived datatype which limits the values of dates to the three US holidays
enumerated. This datatype definition would appear in a schema authored by an 'end-user' and shows how to define a datatype by
enumerating the values in its value space. The enumerated values must be type-valid literals for the base type.
<simpleType name='holidays'>
<annotation>
<documentation>some US holidays</documentation>
</annotation>
<restriction base='gMonthDay'>
<enumeration value='--01-01'>
<annotation>
<documentation>New Year's day</documentation>
</annotation>
</enumeration>
<enumeration value='--07-04'>
<annotation>
<documentation>4th of July</documentation>
</annotation>
</enumeration>
<enumeration value='--12-25'>
<annotation>
<documentation>Christmas</documentation>
</annotation>
</enumeration>
</restriction>
</simpleType>