I think Zeiss used to call it Chebyshev's method. Technically, it is a Chebyshev method.
This is anecdotal, I think I once verified this, but I can't recall. MRS is the method that is supposed to be used when calculating roundness per the ANSI standard. But I could be wrong.
As
RandomJerk said, it's Chebychev's method, so Minsep on PC-DMIS.
From taylor Hobson Minimum Zone Reference Circles (MZCI)It is defined as two concentric circles positioned toenclose the measured profile such that their radialdeparture is a minimum. The Out-of-Roundnessvalue is then given as the radial separation of the two circles.
