Great Program, thanks so much!

To help some of us with a more technical background out, could you be more specific with the possible range of specif values on the following :

   Noise Margin

   Attenuation

   Power level

Also, what is the likelihood of those values changing dramatically over time?  Would it be useful for me to keep monthly snapshots?

Finally, can you please interpret this Bitloading diagram?  I am curious about the gradual degradation as the frequency rises (normal, I would say), but then the funny uptake in the Bitload after 5MHz.  ALso, the two black bars ~3.8 and 5.0 MHz.