Can the XML <any> element restrict what datatype it stores?

[Meredith]

Question:

Can the XML <any> element restrict what datatype it stores? I am
trying to write an extensible schema that has an element containing
unbounded <any> elements of boolean type. Is it possible to control
the <any> element within the schema or must something like an XSLT
template be applied instead?

I'd like to do something like this:

<xsd:complexType name="subscribe">
<xsd:element name="dataType" minOccurs="0">
<xsd:any namespace="##any" type="xsd:boolean" minOccurs="0"/>
</xsd:element>
<xsd:element name="userName" type="xsd:string"/>
</xsd:complexType>

Thanks for your help!
Meredith