"Purpose: This specification covers axis and motion nomenclature for numerically controlled equipment. These requirements are intended to standardize programming and tape preparation and facilitate the interchangeability of control tapes by prescribing the letter designation of each axis@ and the positive direction of each axis. Classification: The specification includes standards for Class III (Positioning)@ Class IV (Contouring)@ and Class III/Class IV (Contouring/Positioning Combination Systems) numerically controlled equipment. Definitions of terms used in this standard are in accordance with the current version of the EIA Automation Bulletin@ ""Glossary of Terms for Numerically Controlled Machines"". Revisions to these standards will be proposed as technical progrees warrants. "