This International Standard specifies the characteristics of the standard basic rack tooth profile for cylindrical involute gears (external or internal) for general and heavy engineering.

This International Standard applies to the standardized modules specified in ISO 54.

The defined profile does not take into account the possible cut-off of the height of internal teeth. This height is to be calculated for each case.

The standard basic rack tooth profile defined in this International Standard constitutes a geometrical reference for a system of involute gears in order to fix the sizes of their teeth. It does not constitute a definition of a cutter, but a cutter may be defined from this standard basic rack tooth profile in order to realize a conforming profile.