What is the file extension of Classic Mac OS applications?

[Windows XP]

I know the macOS (formerly OS X) application file extension is .app, but what was the file extension for Classic Mac OS applications?

 

[rsolberg]

There is no file extension for classic Mac OS application binaries as classic Mac OS doesn't use file extensions to determine file type.  The file type and creator code are stored in the corresponding resource fork for a given file.  The exception is when files from/for a different OS/filesystem are present, then an extension like PC File Exchange or Macintosh Easy Open is used to associate applications with extensions on files missing the resource data.  On OS 8 and above, this compatibility functionality is built in.

 

[AlpineRaven]

yep that above.

If you have windows/DOS disk that you want to use - you'll need PC File Exchange control panel installed on that Mac to recognise file format coming in, it'll convert to whatever needed to be.

Cheers

AP

 

[Windows XP]

OK, I learned that type codes are used instead.

Well then, what is the type code for regular Classic Mac OS applications?

 

[nglevin]

For practical purposes, it really doesn't matter as long as you never strip the resource forks from your Macintosh files by copying them to a not-Macintosh formatted disk.

I suggest taking a look at the resource fork Wikipedia for all these details. It should answer all of your questions.

 

[Windows XP]

Update I saw type codes on Wikipedia and APPL seems to be the type code for it.

 

[Crutch]

That is the correct File Manager file type, yes. In order for the Finder to recognize a file as an executable application and allow you to launch it by double-clicking, it must have type ‘APPL’. Of course in order to actually work, it must then have at least one CODE resource in it.