This comment is appropriate here then!

Traditionally, EK ran a release process for all B&W films to verify the speed and curve shape of all films before going out into the trade. The developer used was D-76. They may have changed, but when I was "there" that is what was used. And, the speed ratings were given for an approximate contrast of 0.6 as I have noted before.

Thus, if a Kodak film is developed to a contrast of about 0.6 - 0.8 (professional to consumer range) the speed should be spot on for the box rated ISO speed.