So then… is there no way to get it to playback then?
I took a look - it seems there is a magic string "film" at offset 0 so I will add this.
If you download the RAW version - the fork is missing for sure, but they provide the sit/zip/etc that preserve the fork as well. Normally apps do allow you to do a File->Open to work around missing type/creator - though I'm in an emulator right now and MacFilm doesn't like that.
After trying with a bunch of different files, it's interesting that some .img were given 'Disk Copy document' which opens with 6.3.3 while others were given 'Disk Copy 4.2 disk image' which still opens with 6.3.3. Along a similar vein, .sit were given a variety from 'Stuffit 1.5.1 archive', 'Stuffit Deluxe 3 archive', or 'Stuffit Expander document'.
Fix-a-Fork didn't seem to do anything to .dmg .cdr .iso .image .toast .jpg .html or .png files. I would guess .dmg and .image goes to Disk Copy, where .cdr .iso .toast goes to Virtual CD/DVD Utility, and .html .png .jpg goes to browser?
DC6 is a very odd format and there is almost no documentation - all the metadata is in the fork so it's difficult to tell without guessing if it's a DC6 or not.
If it's DC42 I can look for markers at offsets to tell, and those should be right.
sit 1-5 should be handled correctly as I look for markers at offsets.
dmg is too new - cdr and iso i'll add - toast should be correct.
Images are all set to Graphics Converter types (maybe a bad assumption, maybe not)
html is set to TEXT MOSS (guessing mozilla?)
But all these comments really get to the heart of the next thing to think about - some users prefer different apps for different files - eg: I want to use Netscape vs IE vs PageMaker for my html documents. This gets a little less important later (in OS8+) with internet config and assigning file types by extension at the system level.
Thanks for all the testing and feedback!