The text content (textual child nodes) can not be validated.
The child elements can be validated.
<xs:element name="book"> <xs:complexType mixed="true"> <xs:all> <xs:element name="title" type="xs:string"/> <xs:element name="author" type="xs:string"/> </xs:all> <xs:attribute name="isbn" type="xs:string"/> </xs:complexType> </xs:element>