From context they mean lossless compression audio format, and standard AIFF and WAV are uncompressed PCM. On the other hand, AIFF does have a compressed varian

From context they mean lossless compression audio format, and standard AIFF and WAV are uncompressed PCM. On the other hand, AIFF does have a compressed variant ("AIFF-C") spec'd in 1991 [1], which I suspect the author wasn't aware of. [1] https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/AIFF.html https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/A...