Datum value refrenced in another Datum?

System

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cancer


http://ourGSP.com/search?text=$GBM001

org.sw.livesite.external.runtime.XML
getService


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I am wanting to use the value of the datum with the id GBM001 in the the above example as part of the value for the datum with the id of NAMED_RESOURCE. Is this possible? I cant find an example of how to reference datum values in the content xml.

Thanks for any help