need of .snd files

http://reference.wolfram.com/mathematica/ref/format/SND.html says they are identical to .au file format.

Does that refer to the original Macintosh 'snd ' sound file format? ** Note the space - all "Classic" Mac file types were 4 characters (the space here is counted as the fourth character). Or does it maybe refer to a PC file type (usually of 3 characters), which might or might not be compatible?

There was a fantastic sound tool called Soundmachine made for System 7. Wonder if it supported the sound formats in question.