XML Tutorial/XML Schema/simpleContent

As simple content models

<?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:simpleType name="empty">
    <xs:restriction base="xs:string">
      <xs:enumeration value="" />
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="br">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="empty">
          <xs:attribute name="id" type="xs:ID" />
          <xs:attribute name="class" type="xs:NMTOKEN" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

Creating Elements with Simple Content and Attributes

When declaring an element that has simple content, you start with a basic element declaration: 
<element name="phone"> 
    <!-- Specify type here --> 
</element> 
Within the element declaration, you include a <complexType> declaration in which you specify that you want your element to have simple content. 
You do this by creating a <complexType> declaration that contains a <simpleContent> element. 
The <simpleContent> element indicates that the <complexType> cannot contain child elements. 
It may contain attributes, but otherwise the content will be defined by a simple type.
<element name="phone"> 
    <complexType> 
        <simpleContent> 
            <!-- Specify type here --> 
        </simpleContent> 
    </complexType> 
</element> 
Within the <simpleContent> element, you can create an <extension> declaration. 
You must use an <extension> declaration because you will be extending an existing data type by adding attribute declarations. 
<element name="phone">
  <complexType>
    <simpleContent>
      <extension base="string">
        <attribute name="kind" type="string" default="Home" />
      </extension>
    </simpleContent>
  </complexType>
</element>

Any of the following examples are allowable <phone>elements based on the previous declaration: 
<phone kind="Home">001-909-555-1212</phone> 
<phone>001-909-555-1212</phone> 
<phone />

Defining Elements to Contain Only Text

File: Schema.xsd
<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  targetNamespace="http://www.wbex.ru" xmlns="http://www.wbex.ru"
  elementFormDefault="qualified">

  <xsd:complexType name="popType">
    <xsd:simpleContent>
      <xsd:extension base="xsd:integer">
        <xsd:attribute name="year" type="xsd:integer" />
      </xsd:extension>
    </xsd:simpleContent>
  </xsd:complexType>
  <xsd:element name="population" type="popType" />
</xsd:schema>
 
File: Data.xml
 
<population xmlns="http://www.wbex.ru" year="1999">445</population>

element based on simple type

File: Data.xml
<?xml version="1.0"?>
<INVENTORY>
   <BOOK InStock="true">
      <TITLE>title 1</TITLE>
      <AUTHOR Born="1835">
         <FIRSTNAME>Mark</FIRSTNAME>
         <LASTNAME>Twain</LASTNAME>
      </AUTHOR>
      <BINDING>hardcover</BINDING>
      <PAGES FrontMatter="8">298</PAGES>
      <PRICE>5.49</PRICE>
      <DATE>2000-03</DATE>
      <ISBN>9-9999-9999-9</ISBN>
   </BOOK>
</INVENTORY>

File: Schema.xsd
<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <xsd:element name="INVENTORY">
      <xsd:complexType>
         <xsd:sequence>
            <xsd:element name="BOOK" type="BookType" 
               minOccurs="0" maxOccurs="unbounded"/>
         </xsd:sequence>
      </xsd:complexType>
   </xsd:element>
   <xsd:complexType name="BookType">
      <xsd:sequence>
         <xsd:element name="TITLE">
            <xsd:complexType mixed="true">
               <xsd:sequence>
                  <xsd:element name="SUBTITLE" type="xsd:string"
                     minOccurs="0" maxOccurs="1"/>
               </xsd:sequence>
            </xsd:complexType>
         </xsd:element>
         <xsd:element name="AUTHOR">
            <xsd:complexType>
               <xsd:sequence>
                  <xsd:element name="FIRSTNAME" type="xsd:string"/>
                  <xsd:element name="LASTNAME" type="xsd:string"/> 
               </xsd:sequence>
               <xsd:attribute name="Born" type="xsd:gYear"/>
            </xsd:complexType>
         </xsd:element>
         <xsd:element name="BINDING">
            <xsd:simpleType>
               <xsd:restriction base="xsd:string">
                  <xsd:enumeration value="hardcover"/>
                  <xsd:enumeration value="mass market paperback"/>
                  <xsd:enumeration value="trade paperback"/>
               </xsd:restriction>
            </xsd:simpleType>
         </xsd:element>
         <xsd:element name="PAGES">
            <xsd:complexType>
               <xsd:simpleContent>
                  <xsd:extension base="xsd:positiveInteger">
                     <xsd:attribute name="FrontMatter" 
                        type="xsd:positiveInteger"/>
                  </xsd:extension>
               </xsd:simpleContent>
            </xsd:complexType>
         </xsd:element>
         <xsd:element name="PRICE">  
            <xsd:simpleType>
               <xsd:restriction base="xsd:decimal">
                  <xsd:minExclusive value="0"/>
                  <xsd:maxExclusive value="100"/>
               </xsd:restriction>
            </xsd:simpleType>
         </xsd:element>
         <xsd:element name="DATE" type="xsd:gYearMonth" minOccurs="0"/>
         <xsd:element name="ISBN">
            <xsd:simpleType>
               <xsd:restriction base="xsd:string">
                  <xsd:pattern value="\d{1}-\d{4}-\d{4}-\d{1}"/>
               </xsd:restriction>
            </xsd:simpleType>
         </xsd:element>
      </xsd:sequence>
      <xsd:attribute name="InStock" type="xsd:boolean" use="required" />   
   </xsd:complexType>
</xsd:schema>

The simpleContent element is used if the complex type may only have text content

The difference between this and a simple type is that it may carry one or more attributes. 
The only children that are permitted for this element are the restriction and extension elements. 
<?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="Person">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="age" type="xs:integer" />
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>