This comes from ISO 2768-1 , which covers linear and angular dimensions. The "m" stands for the medium tolerance class, the most widely used standard in CNC machining and general manufacturing because it balances cost with functional accuracy.
For mathematical expressions that I may use, I will use $$ syntax without newlines, for example: $$x+5=10$$. iso 2768 m h
The designation is composed of two distinct parts representing different categories of tolerance: This comes from ISO 2768-1 , which covers
Correct notation in title block or near general note: This comes from ISO 2768-1