[Elecraft] What does 72 mean

[Ron D'Eau Claire]

I have a question. We all know what 88 means (Love and Kisses) 
and 73 (Best regards and goodbye) but I am hearing 72 both on the air
and some of the letters on this reflector. Can someone define 72 so we
can all know what it means. 73

Ken Christiansen W0CZ 
K2-1031
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Some of the QRP fraternity use it to indicate that they are QRPers...
It's 73, only a little less, Hi.

For me it's still 73 (Best Regards), from

Ron AC7AC
K2 # 1289

...guess I'm just a traditionalist.