[s-cars] How does EDL work?

[henryb at aciworldwide.com]

I just purchased a 1997 S6 and I understand that it uses an Electronic 
Locking mechanism for the Rear Differential Lock.  On many of my previous 
quattro's: '92 S4, '95 A6, '90 CQ, '88 5K TQW, they all had some manual 
mechanism to lock the differential.  I have not seen any good technical 
write-up on exactly how does the EDL work.  Does anyone know of a good 
tech white paper on the web that describes this system well?  I have also 
heard that later EDL systems work on both Front and Rear Diff's???  Is 
that different then the system that I have on my S6?  Any feedback would 
be appreciated.

Thanks,
Brent.