n00b q: Setting an ID in an XSL stylesheet

[Vosper]

I'm sure this is an obvious question...

I have an XSL stylesheet, which looks like this:

<xs:element name="person">
<xs:complexType>
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="biography" type="xs:string"/>

I want to use the "name" element as also the ID for the "person" element, so that I can use .getElementByID in DOM. I have tried changing the "name" tag to:

<xs:element name="name" type="xs:ID"/>

but I get this error when validating an xml document that uses this stylesheet:

'John Smith' is not a valid value for 'NCName'.

I'm sure this is simple! Any help would be greatly appreciated