[Elecraft] OT: 20m moving QRM.

[Mike]

I have no way of verifying this, and I only date back to the 1950s as 
both ham and commercial operator. But always understood that the N (as 
in QRN) meant the interference was from 'Natural' sources and the M (as 
in QRM) meant that the interference was from 'Man-made' sources.
Guess only those who formulated the original Q-codes could tell 
us.....and they will all be SK by now!
73 de Mike, zl1mh.