ASME Y14.5

ASME Y14.5 is a standard published by the American Society of Mechanical Engineers (ASME) to establish rules, symbols, definitions, requirements, defaults, and recommended practices for stating and interpreting Geometric Dimensions and Tolerances (GD&T). ASME/ANSI issued the first version of this Y-series standard in 1973.
Overview.
ASME Y14.5 is a complete definition of Geometric Dimensioning and Tolerancing. It contains 12 sections which cover symbols and datums as well as tolerances of form, orientation, position, profile and runout. It is complemented by ASME Y14.5.1 - Mathematical Definition of Dimensioning and Tolerancing Principles. Together these standards allow for clear and concise detailing of dimensional requirements on a product drawing or electronic drawing package as well as the verification of the requirements on manufactured parts. Effective application of GD&T allows for parts to be verified by dimensional measurements, gauging, or by CMM.
History.
The modern standard can trace its roots to the military standard MIL-STD-8 published in 1949. It was revised by MIL-STD-8A in 1953 which introduced the concept of modern GD&T "Rule 1". Further revisions have continued to add new concepts and address new technology like Computer Aided Design and Model-based definition. A list of revisions follows: