iv boundaries. Where a tool is shown in addition to the product, the tool is shown in color to distinguish it from the product. Interpretation fi gures are provided to show the tolerance zones resulting from tolerance specifi ca- tions. Tolerance zones and part variations in these fi g- ures are suffi ciently exaggerated to make them visible. Uppercase letters are used for notations that are part of the drawing. Lowercase letters are used for instructional notes and information. One exception is that degrees of freedom notations (x, y, and z and u, v, and w), within a feature control frame, are made with lowercase letters as required by the ASME standards. Dimensioning and tolerancing of a part requires application of principles in the ASME Y14.5 standard. When defi ning tolerances on a model, conformance with ASME Y14.41 is desirable. GD&T: Application and Interpretation shows how to apply the principles in these standards to many situations and offers sug- gestions regarding the extension of the principles to situations not shown in the standards. Care must be taken in the extension of principles. Otherwise, a violation of the standards or unclear requirements could result. Compliance with the standards is ulti- mately the responsibility of the person applying or interpreting dimensions and tolerances. About the Author Bruce A. Wilson, author and illustrator of GD&T: Application and Interpretation, has an international reputation as a leader in Dimensional Management and Geometric Dimensioning and Tolerancing (GD&T). He has contributed to the development of national and international standards and is known for his work in professional training and consulting. Mr. Wilson is certifi ed by ASME as a Senior Level Geometric Dimen- sioning and Tolerancing Professional. Mr. Wilson has more than 30 years of partici- pation in ASME Y14.5 subcommittee standards development. He served as chairman of the ASME Y14 SC5 national commit- tee during the nine-year development of the ASME Y14.5-2018 standard. He served as chairman of the ASME Y14 SC5 work- ing group for location tolerances during the 15-year development of the ASME Y14.5-2009 standard. He served as a member of ASME Y14 SC5 during the development of the ASME Y14.5M-1994 stan- dard. Mr. Wilson has served for more than 25 years as a member of the ASME Y14 committee that has oversight of all Y14 engineering documentation standards, and he was an offi cer on multiple other Y14 subcommittees. He served as a member of the US advisory group for ISO standards. Mr. Wilson has extensive training and consult- ing experience. He has taught GD&T to students from the United States, Europe, and Asia. His expe- rience includes curriculum development, teaching, management of training programs, and instructor development. As part of his engineering responsi- bilities, Mr. Wilson led training programs for thou- sands of design engineers, manufacturing engineers, machinists, tool designers, tool makers, quality engi- neers, inspectors, supplier managers, and managers. He has advised executives regarding the technical needs and health of their organizations. Mr. Wilson’s industrial experience includes responsibilities ranging from design engineer to program manager and industrial consultant. He was recognized as a Technical Fellow in The Boeing Company. His design engineering experience includes precision mechanisms, electromechanical, optics packaging, electronics packaging, pneumat- ics, spacecraft, and aircraft. His experience spans companies ranging from 20 to 150,000 employees. Mr. Wilson is an industrial leader in devel- oping, deploying, and applying the discipline of dimensional management. He led teams to establish product system requirements, complete 3D variation analysis, apply tolerances, communicate require- ments to production, defi ne locating methods for major assemblies, and implement quality assurance measures related to dimensional variation. His vari- ation analyses and assembly concepts resulted in product cost savings greater than 50% and elimi- nated assembly tooling costs for major aircraft struc- ture. Mr. Wilson has multiple United States patents, including some that are for calculation methods used to assess variation effects. Mr. Wilson’s education includes Bachelor of Science and Master of Science degrees from Southern Illinois University-Carbondale and a Bachelor of Science degree from Saint Louis Christian College. Senior