[Sephiroth]

Horse,

TYhanks for the trouble you've gone to in elaborating the question. The BPI+ observation of mine can be ignored - it was a long winded way of sying "whatever is associated with your authorised config".

The "average power" explanation is a simplification (that I qualified) because the user sees only the channels posted by the modem stats. He/she takes an average, but has no idea what power level adheres to the hidden channels. So, to explain the concept, the "average" is introduced.

Your point about +/-17 dBmv introduces another sort of interesting observation. Wouldn't you say, looking at the upper end, that 17 dBmv is the limit in a well built modem after which leakage into adjacent channels occurs. 33 dBmv seems to me to be a "busting" point (using the +3dB method) beyond which it is utterly useless as distinct from the 17 dBmv point.