How can I add max length, required attributes: Yes in XML schema? - xsd

Question

I know there are two ways to define simple elements in XML schema. How can I add only maxlength and required attribute YES to simple element definition. in the following two examples.
<xs:element name="Xyz">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:minLength value="1"/>
<xs:maxLength value="4"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element name="Xyz" type="xs:string" minOccurs="0" maxOccurs="1"/>

Answer 1

Define your restricted text content as a global (=named) <xs:simpleType> then use this as a base type for <xs:extension> that you need when create a new type by extension to add the attribute.
Type definition of an element that has attributes must be <xs:complexType>. Then again if the element content can be only text or attributes but not elements, the content must be defined as <xs:simpleContent>. Sample code below.
<!-- definition of the restricted string -->
<xs:simpleType name="restrictedLength">
<xs:restriction base="xs:string">
<xs:maxLength value="4" />
</xs:restriction>
</xs:simpleType>
<!-- definition for the element with an attribute and text content -->
<xs:element name="Xyz">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="restrictedLength">
<xs:attribute name="YES" use="required"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
For more complete explanation on extending simple content elements with attribute see this:
http://www.xml.com/pub/a/2001/08/22/easyschema.html