The International Organization for Standardization (ISO) and Deutsches Institut für Normung (DIN, the German Standards Institute) have produced a set of standards governing gear teeth.
ISO is a worldwide developer of voluntary consensus standards applicable to a range of industries. DIN is a German standards organization that acts as the ISO body for Germany.
DIN 3967 is part of a series of standards that specifies tolerances for cylindrical gear teeth. Other standards in the series include DIN 3961, 3962, 3963 and 3964. It provides information on the deviation of tooth traces, on recommended tooth thickness and on symbols and designations for gear teeth tolerance terminology, among other topics.
DIN 3967 is available for purchase on the DIN website. It is available in English, German and Spanish. As of January 2011, the cost is approximately €75 (about US$103, as of January 2011) for the German version and approximately €94 (about US$129) for either of the translations.