.zip is required for .iso and .cdr images because of the space savings. Also it's OK for OS X stuff.

NOW if someone uploads stuff with resource forks as .zip list them here and I'll fix up the forks. I'll need someeone to change it from dmg to sit though because my current computer can't make sit v.5 files.

If you have an app that can create a v. 5 .sit in OS X, let me know!

sorry, I've been rather busy lately ... but I'll do these when I have a chance.

also for .toast images ... though there's debate on whether .sit or .zip is better.

Mmm, I'm sure there have been Mac ZIP programs as far back as Mac OS 7. We only have to ascertain if they can unzip files created in Mac OS X.

Edit: Replaced 'xxx 7' with 'Mac OS 7'. - IIGS User

While they unzip files with data forks only properly, they completely destroy resource forks and Finder attributes. So for an .iso, .cdr, or .toast image, they're OK, but for Mac apps they're no good.

For the Classic OSes and environment I´d go for the SIT format no matter what to compress, as long as it stands between SIT and ZIP. SIT archives are generally smaller than ZIP, they can be handled in both Classic OSes and in OSX. There´s really no need to expand/unstuff archives under other OSes as they tend to destroy the game content. Certainly no need to create archives under other OSes than Mac OS for the same reason mentioned before.
Stick to SIT and leave ZIP for other things than games/apps for the classic Macs.

@MacWise: I've done tests of this. Just use .sit (except for .iso, .cdr, and .toast images) !

@Balrog: Cool. What are the results? Can both kind files be opened under Classic with StuffIt? I'm under the impression zips compressed with the Terminal don't preserve resource forks unless the user includes a special command (like MacZip) and those compressed with the Finder do preserve them but somehow get mangled.

Using the 'zip' command in terminal seems to just throw away resource forks and Finder flags.
Using the "create archive" command in Finder causes the forks to be split up into AppleDouble files, in a folder that looks like '__MACOSX/._file' . Stuffit for OS X handles this, but no Classic OS unzip utility can handle it.

A file that's been compressed using Finder can easily be fixed. I haven't gotten around to fix those few yet ... to busy.

I´ll put another stick into this discussion with the result of a compression test I´ve done.

I´ve used 'StuffIt' v 12 (.SIT w backward compatibility) and 'BetterZip' v 1.8.1 (.ZIP/.7z w best compression). The main copy was made from a CD-ROM with the game 'Forgotten' using 'Toast Titanium' v 9.0.4 under Mac OS 10.4.11. The image was mounted under emulation in OS 9.0.4 as a Toast image using 'Virtual DVD-ROM/CD Utility' then copied with 'ShrinkWrap' 3.5.1 into 'Disk Copy 6.3.x'-format; one compressed and one uncompressed.

The result is as follows:
Toast image
- native 640.3 MB
- StuffIt archive 410 MB
- BetterZip/Zip 432.7 MB
- BetterZip/7zip 316.6 MB

ShrinkWrap/Disk Copy 6.3.x compressed
- native 485.7 MB
- StuffIt archive 440.6 MB
- BetterZip/Zip 445.5 MB
- BetterZip/7zip 356 MB

ShrinkWrap/Disk Copy 6.3.x uncompressed
- native 640 MB
- StuffIt archive 410 MB
- BetterZip/Zip 432.7 MB
- BetterZip/7zip 316.5 MB

Conclusion:
7Zip seems to make the best of compression followed by StuffIt and last the Zip format. However 7Zip is AFAIK not available for Mac Classic systems.
NB: I´ve not made any reflections over the ability of preserving specific Mac content as I used a complete disk image.

Then just use Stuffit. Though it would be nice if we could have the 'unstuff' binary for Linux (and maybe the 'stuff' one as well, though I don't know if that is warez or not ... this would be version 5.x). I have the binaries, just not sure where to upload them.

Please use Disk Copy, not ShrinkWrap for images, if possible.

I think the DropStuff/Expand are free, at least use to be bundled with the Mac OS systems, even early OSX, as 'Internet Apps' IIRC.
Edit: found this re .SIT on Linux; http://linuxmafia.com/faq/Apps/stuffit-archives.html
What´s the problem with ShrinkWrap? I´ve always resorted to the Disk Copy format when using it as a more accessable format in distribution, does Shrink Wrap bad images in this format? I know the native Shrink Wrap format could be troublesome.

@SwedeBear: Both Disk Copy and ShrinkWrap images use resource fork, so even if 7-Zip compress them more than StuffIt, they're rendered useless. Balrog says zip is OK for CD images, but as Attila said on the Civilization II Gold page: "As long as people keep using ZIPs they're going to keep forgetting not to zip apps. Stuffit is the way to go for the Mac Garden." I agree with him.

@MacWise: yep, exactly my thoughts though I did not express them here. Thought it could be interesting with a comparision done with 'the real stuff' before further discussions. But my conclusion is also .SIT as a general archive, even for CDR/ISO. The Expander exists to all system concerned.

The problem with .sit is that there no good .sit v5 archiver for OS X, so those of us without a Classic Mac are left out.

A .sit inside a .zip is fine though.

Also, there is a dmg2img utility for Linux which turns dmg files into raw img images that can be mounted with 'mount -o loop ...' ... I wonder if there's a similar .img format for Classic Mac OS....

Or for the peeps running this in emus, like me; install several systems on different images. OS 9 can be installed on HFS thus a recognizable disk format back beyond/before OS 8. A compact install of OS9 can be done on a 200MB leaving a good amount of free space on it.

My mistake on the Civ II pages, all I had to do was stuffit the 1MB (or so) update before I included it in the ZIP archive.

Stuffit v5 on a CD disc image is so painfully slow, Stuffit v7 is only slightly better, OSX ZIP races through the image.

I'll fix the two Civ uploads when I can spare the bandwidth. But they will still be Toast images (another topic), OS9 Disk Copy just doesn't want to touch multi-format discs (Data and Audio).

Toast is fine, at all.