The paper is based on:
Alternatively, if separation is required:
The selects the medium class (Part 1), and the "H" selects the fine class (Part 2 – geometricals). This combination is widely adopted for general machining, turning, milling, and sheet metal work.
Geometrical tolerances control the "shape" of the part rather than just its size. Class "H" is the strictest category in this part of the standard. Nominal Length Range (mm) Permissible Deviation (mm) Over 10 to 30 Over 30 to 100 Over 100 to 300 Over 300 to 1000 Over 1000 to 3000 Sources: Waterson , ZEISS Quality Forum Other Class "H" Geometrical Tolerances: General Tolerance - ISO 2768 1 & 2 - ZEISS Quality Forum