ISO 2768 was built primarily for metal removal (machining) and sheet metal fabrication. For highly flexible plastics, rubbers, or complex 3D-printed parts, standard machining tolerances may be unachievable or irrelevant.
Instead of writing ± values for every single hole or edge, one note covers everything non-critical. general tolerance iso 2768-mk
Geometric tolerances: ISO 2768-2 class k (medium) ISO 2768 was built primarily for metal removal
Refers to ISO 2768-1 , covering linear and angular dimensions (lengths, diameters, and angles). or complex 3D-printed parts