The optics industry has helped to shape these standards for indicating tolerances. At the same time, methods of measurements are becoming standardized, so not only does everyone understand tolerances, but the relevant optical testing also provides the same output from anyone. An important aspect of standardization, probably unnoticed, is the education process it implies. Continued updating of standards provides a basis for spreading practical and theoretical knowledge on the subject. This should increase the overall quality of production, if only because of the improved information exchange between development and production.... Meet the author Michael Bray is manager of MB Optique, a company he started in 1999 in Paris. He has a PhD in optics from the École Supérieure d'Optique in Orsay, France. He also convenes an International Standards Organization working group on drawings for optical elements and systems in the subcommittee for fundamental standards for optics and optical instruments.