Are you talking about the .acd files? When you import a Humminbird track into Autochart, it creates an .acd file of your track.
Lets say you import 000.ht Humminbird Track into AutoChart. AutoChart then basically just creates a 000.acd autochart file. You then edit and manipulate that 000.acd autochart track, and create maps from the .acd files.
If you import an .ht track file, it creates the .acd file in the same location as your .ht track file. In other words, if you didn't copy your .ht files onto your computer from you sd card, before importing them into Autochart, it created those .acd files on your sd card.
Import your sonar (.dat) or track (.ht) file into AutoChart, and you should see an .acd AutoChart file appear on your card.
I think that's what you're looking for anyways?