Maybe its a bit off topic but week or so ago I accidentaly deleted one RAW photo. Since I already deleted it from card too at first I was sure it was lost forever. But wait, when you delete photo from card it isn't really deleted, just information in file allocation table is changed. Since I wasn't shooting too much after clearing memory card there was still possibility that my photo wasn't overwritten yet.
I didn't wanted to buy some recovery program to restore single image so I used free PhotoRec. Yes, it found my file and it was identified as TIFF. Data converter correctly identified is as RAW and it opened correctly. I wasn't investigating it further, but it seems that ARW format may be simply TIFF image + some additional data stored by camera. If its true then most likely cRAW format may be simple compressed TIFF + additional camera data. However TIFF may use JPEG compression
Anyway, just wanted to share this info.