The simpleType element defines a simple type and specifies the constraints and information about the values of attributes or text-only elements.
<simpleType id=ID name=NCName any attributes > (annotation?,(restriction|list|union)) </simpleType>
(The ? sign declares that the element can occur zero or one time inside the simpleType element)
This example defines an element called “age” that is a simple type with a restriction. The value of age can NOT be lower than 0 or greater than 100:
<xs:element name="age"> <xs:simpleType> <xs:restriction base="xs:integer"> <xs:minInclusive value="0"/> <xs:maxInclusive value="100"/> </xs:restriction> </xs:simpleType> </xs:element>