used TC past three years. switched to TRT. now i use the XDF file when modifying my .bin 1. what exactly is an XDF file? 2. why is it necessary? TC does not use one? 3. what is the advantage of using XDF? 4. why would one need more than one for a specific mask? seems one is all that is needed. 5. what am i missing (besides the ultimate tune) ?

1) An XDF is TunerPro's ECM definition file. Similar to a TDF that Tuner Cat uses. Without it you can't edit a bin in TunerPro. It tells TunerPro what the items are in the bin (constant, flag, table, etc,) and where they are located.

4) Some XDF's are better than others and in my Case on $58, there are 2 Bar XDFs for stock boost and 3 Bar XDFs for bins with the 3 Bar code hacks.

That should answer your questions.

makes sense. i forgot i was using a .TDF in TC. thanks.

does one ever need more than one XDF file for a specific mask? i am using EBL.XDF. i assume only one exists for that mask.

used EBL and TP-RTfor 3 days now so in infancy.

No, you should never need more than one for a mask. As Paul says, since most XDFs are user created (well, all of them, since I'm a user too), some are more complete than others. You might find that one XDF for a mask contains things that another for the same mask does not, and that the first has items the second does not, etc. I leave it up to you (guys) to find, create, and use the best XDFs. This is something that makes TunerPro more "open."

Unfortunately one of TunerPro's great powers is also a weakness.

It is great to be able to create your own definitions.
I tried to put together a database to sort out differences between all of them I found for $8D but it failed due to too many ways to sort the items.

Maybe a thread discussing how to create a compare utility for the ADS and XDF (or the new ALDL format) would spark some interest in getting something done there.
With some input from "The Great M", we could put it together.
He has enough to do without adding this feature creep.
Nice winter project.