[TenTec] R1 and R2 Levels... ???

[WmLB at prefer.net]

Not Ten-Tec related, but I figure someone on this list has probably 
got the answers.

The propagation reports are using new terminology (to me anyway)  to 
forecast conditions related to radio propagation.  "R1 Level" or "R2 
Level" (maybe there is an R3 and a R4 too)

Does anyone know where I can find a explanation of these terms?


Bill

Costa Mesa, CA
Amateur Radio Station: W6WLB