ADT property data is stored with the object, not in attributes in tags. ADT tags are Multi-View Blocks that use view blocks with attributes to display selected property data, but the data resides on the object, and the tag pulls the displayed information from the object's data.
If you want to learn more about Property Set Definitions, Schedule Table Styles and Custom Tags, take a look at Brain Dumps No. 13 and 15, by Mr. Matt Dillon, at http://home.earthlink.net/~ccyanchar/ .
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David Koch
Member of the Autodesk Discussion Forum Moderator Program