[bvw]

Sorry, I don't follow your explanation. Is "base 10" some term of art in his field that is at variance from the normal meaning of that techical term?

[John Jamieson]

Yes, heating and cooling calculation from HVAC contractors do the same thing in degree-days using 68 for heating and say 76 for cooling as the base.

It has nothing to do with number systems like octal, decimal, binary, or hex.