SIDE ATR Fat partition?

I finally got around to playing with the SIDE cart I purchased many moons ago.  I have the cart divided between SpartaDos and a FAT Partition.  I know I can launch XEX files from the FAT, but I'm not sure about ATR files.

Am I missing something, or is that not possible?  I seem to remember some mention of maybe having that as a future feature.  

Any clarity would be great.

Thanks