XSD: How to derive a simpletype both to add a attribute to it and to restrict the acceptable value of it

Question

for example To validate the following element:

 100 

The constraint I want on the text

Answer 1

It is not possible without adding a new type; you can't extend and restrict at the same time.

Answer 2

Extending a simple type with attributes

Inspired by Petru Gardea's answer to XSD custom type with attribute and restriction, I have come up with a solution that should work for you. Your element must be a complexType extending the restricted simpleType with an attribute:

<!-- simple type that we want to extend with an attribute -->
<xs:simpleType name="populationType">
    <xs:restriction base="xs:integer">
        <xs:minInclusive value="0"/>
        <xs:maxInclusive value="1000"/>
    </xs:restriction>
</xs:simpleType>

<!-- extending a simple content element with an attribute -->
<xs:element name="population">
    <xs:complexType>
        <xs:simpleContent>
            <!-- populationType is a simple type -->
            <xs:extension base="populationType">
                <xs:attribute name="class" type="xs:string" use="required"/>
            </xs:extension>
        </xs:simpleContent>
    </xs:complexType>
</xs:element>

Extending multiple types with the same set of attributes

In addition, if you want to extend multiple types with the same set of attributes, you could use the xsd:attributeGroup as suggested in C. M. Sperberg-McQueen's answer to XSD: Adding attributes to strongly-typed “simple” elements:

<!-- several types declare this set of attributes -->
<xs:attributeGroup name="extensible"> 
    <xs:attribute name="att1" type="xs:string" />
    <xs:attribute name="att2" type="xs:string" />
</xs:attributeGroup>

<!-- simple type that we want to extend with attributes -->
<xs:simpleType name="populationType">
    <xs:restriction base="xs:integer">
        <xs:minInclusive value="0"/>
        <xs:maxInclusive value="1000"/>
    </xs:restriction>
</xs:simpleType>

<!-- extending a simple content element with two 'inherited' attributes -->
<xs:element name="population">
    <xs:complexType>
        <xs:simpleContent>
            <!-- populationType is a simple type -->
            <xs:extension base="populationType">
                <xs:attributeGroup ref="extensible"/>
            </xs:extension>
        </xs:simpleContent>
    </xs:complexType>
</xs:element>

This would validate the following xml element:

<population att1="AAA" att2="BBB">100</population >