Work item template

Hello!
I want to create XML work item template. This template includes some work items with custom attributes. The attributes are links to other work items, and i want to fill these atributes in the template. How can i do this?

I try following example but doesn't run.

...
<rtc_cm:customWorkItem rdf:ID="item0">
<dc:title>Custom One</dc:title>
<dc:description>Custom description....</dc:description>
<rtc_cm:plannedFor rdf:resource="${plannedFor:Iteration}"/>
<rtc_cm:filedAgainst rdf:resource="${filedAgainst:Category}"/>
</rtc_cm:customWorkItem>
<rtc_cm:customWorkItem rdf:ID="item1">
<dc:title>Custom two</dc:title>
<dc:description>Custom description....</dc:description>
<rtc_cm:plannedFor rdf:resource="${plannedFor:Iteration}"/>
<rtc_cm:filedAgainst rdf:resource="${filedAgainst:Category}"/>
<rtc_cm:customAttribute rdf:resource="#item0">
</rtc_cm:customWorkItem>
...

Thx.