Define A, B, T in Properties-> Configuration specific, establish equation make dimensions equal to A, B, T, then make a design table defines $PRP@A,
$PRP@B, $PRP@T. The value in Properties-> Configuration specific change with configuration, but not change in equation.
Attached is a model file in 2012.
Thanks
I don't have winrar so I can't open your attachment, but from what I can tell, when you're specifying the file property to drive your dimensions the equation manager will give you a list containing both the document-level custom properties and the configuration-level custom properties. If they have the same name, it may not be obvious which one is driven by the configuration.