Restricting XML attribute content via XSD

I've got some XML like that:

<sometag datatype="xs:string" .../>
<sometag datatype="xs:int" .../>

As one can see, the content of the attribute "datatype" should refer to the basic XML datatypes. Currently I'm using the some self-defined simpleType like the following:

<xs:simpleType name="contentDataType">
  <xs:restriction base="xs:string">
    <xs:enumeration value="string"/>
    <xs:enumeration value="int"/>
    <xs:e开发者_如何学编程numeration value="boolean"/>
    <xs:enumeration value="float"/>
  </xs:restriction>
</xs:simpleType>

Is there a way of restricting the content to the names of the XML basic types via an XSD?

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The names of the XML datatypes aren't datatypes in themselves, so your enumeration is pretty much the only way to do this - that or a regular expression. Either way you need to provide a string based restriction that allows only a list of values or a filter that only allows those values through. I'd choose the enumeration purely for clarities sake.