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In 1940, Parker published Notes on Design and Inspection of Mass Production Engineering Work, the earliest work on geometric dimensioning and tolerancing. His work increased production of naval weapons by new contractors. While little is known about Parker's life, it is known that he worked at the Royal Torpedo Factory in Alexandria, West Dunbartonshire, Scotland. The origin of GD&T is credited to Stanley Parker, who developed the concept of "true position".

5.4 GD&T standards for data exchange and integration.

5.2 ISO/TC 213 Dimensional and geometrical product specifications and verification.

5.1 ISO TC 10 Technical product documentation.

2 Dimensioning and tolerancing philosophy.

BS 8888 provides a self-contained document taking into account a lot of GPS&V standards. There are separate standards that provide the details for each of the major symbols and topics below (e.g. The ISO standards, in comparison, typically only address a single topic at a time. The Y14.5 standard provides a fairly complete set of rules for GD&T in one document. Other standards, such as those from the International Organization for Standardization (ISO) describe a different system which has very different interpretation rules (see GPS&V). One such standard is American Society of Mechanical Engineers (ASME) Y14.5.

There are several standards available worldwide that describe the symbols and define the rules used in GD&T. Two examples are linear dimensions and feature control frames using a datum reference (both shown below). Tolerancing specifications define the allowable variation for the form and possibly the size of individual features, and the allowable variation in orientation and location between features.Dimensioning specifications define the nominal, as-modeled or as-intended geometry.GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features. It tells the manufacturing staff and machines what degree of accuracy and precision is needed on each controlled feature of the part. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describe nominal geometry and its allowable variation. Geometric Dimensioning and Tolerancing ( GD&T) is a system for defining and communicating engineering tolerances and relationships.

Example of geometric dimensioning and tolerancing