Geometrical Tolerances—Separate, Combined or Simultaneous?

The 14 geometrical tolerances defined in ISO 1101 are supplemented by the alphanumerical symbols this standard and some other standards. CZ (combined zone), SZ (separate zones) SIM (simultaneous requirement), which crucial for development of robust measuring programs coordinate machines, were introduced at different times or It is shown that symbol definitions not always complete. Sometimes there no univocal rules their use, which, cases, leads to ambiguity specifications given a designer. also pointed out certain functional requirements can be controlled symbols, it clear if indications equivalent. This makes difficult understand interpret drawing metrologist and, thus, may lead uncertainty assessment product conformity regarding specifications. identified ambiguities problems specification several figures. Corrections additions current standards proposed.