Thanks all
(Bing for G.INP seems to have a very relevant first hit: https://www.increasebroadbandspeed.co.uk/g.inp - thanks for mentioning it )
But because that's likely/possibly not in the cabinet that I'm served from I'll not get too excited.
As long as my connection floats up to the current technical limit, not an incorrect package limit, I'll be happy.
Is a 6dB noise margin the default target?
Yes 6dB is target.
My final question I think ...
What is the maximum data rate quoted? Is it the data rate with 0dB noise margin??