Inconsistency in Nitto stem measurement system

Nitto's measurement systems are very consistent, they just have several.

Defining the same measure "extension" in different ways for different stem products is inconsistent, i.e., lacking consistency in the definition of a quantity, rather than consistency over time.

I started this conversation because the LFGSS threads on stem measurement mentioned in several places that Nitto stems seemed to be about 10mm longer than expected as they use their own measurement system. It turned out that Nitto use two measurement systems which give different values for extension. I thought the information might save someone having to return a mail-order stem that was longer than expected. In my case, I'll measure carefully using the appropriate diagram for the model and hope for the best when ordering.

[ edited after comment from @pop.zr, to correct the direction of the difference reported in earlier LFGSS threads ]