XSD question: Can the name of a simpleType be the name of a built-in datatype?

Hi Folks,

Is this legal:

<xsd:simpleType name="boolean" id="boolean">
       <xsd:restriction base="xsd:boolean">
       </xsd:restriction>
 </xsd:simpleType>

Notice that the name of the simpleType (boolean) is the name of the built-in boolean datatype.

Saxon seems to think it's illegal:

Error: A simple type must not be based on itself

I don't see anything in XML Schema Part 1 that prohibits the name of a simpleType being the name of a built-in datatype.

/Roger