Print copy ASME Y14.5-2009 Standard. The Y14.5 standard is considered the authoritative guideline for the design language of geometric dimensioning and tolerancing (GD&T.) It establishes uniform practices for stating and interpreting GD&T and related requirements for use on engineering drawings and in related documents. GD&T is an essential tool for communicating design intent — that parts from technical drawings have the desired form, fit, function and interchangeability. By providing uniformity in drawing specifications and interpretation, GD&T reduces guesswork throughout the manufacturing process — improving quality, lowering costs, and shortening deliveries. Now, a consensus committee of experts has revised Y14.5 for 21st-century applications. Important changes address: concept of feature of size; datum references and degrees of freedom; composite position tolerances; surface boundaries and axis methods of interpretation; profile tolerances; and symbology and modifiers tools. Additionally, the subject matter has been restructured for better readability, with profile, orientation, and form now in separate sections, and material within sections reorganized. ASME Y14.5-2009 is a replacement of ASME Y14.5M-1994.