From Hydrogenaudio Knowledgebase
Shorten is one of the oldest Lossless audio formats. It was created by Tony Robinson in the mid-nineties.
The reason why it became very popular is that it was the first open source lossless compressor. It gained huge momentum years ago because of this, and to this day it's the most popular format for lossless audio encoding, being used mostly at live recordings (bootlegs) trading communities.