I found another use for mapped tables yesterday that I figure a few people over time will find of use.

Customer has TableA and TableB. They can be related through a common key, which, of course, is important for the map.

My customer needed a tablecount() of TableA. But the "desired" filter for TableA also included criteria from TableB. For instance:

query.filter = "Cond1 = 'x" .and. Cond2 = 'y' .and. TableB->Cond3 = 'z'"

Now, you can't run Tablecount() with such a query, or across tables, or against a set. It occurred to me a mapped table might be the way to go. I set up the map, included just the fields we needed for the query.filter, and it worked as I had hoped. I just stripped the TableB reference from the original query.filter, e.g.:

query.filter = "Cond1 = 'x" .and. Cond2 = 'y' .and. Cond3 = 'z'"
result = tablecount("MapTableName", query.filter)

Sure, this can be done in other ways but I think this provides one of the simplest approaches I've used yet, and is easiest for most to implement.