NISTIR 7716 - Recommended practice extensions for GD&T in STEP-AP210 in the context of electronic connectors

Oct 24, 2026

Recommended practice extensions are defined to represent geometric dimensioning and tolerancing (GD&T) within STEP AP 210 (ISO-10303:210) for packaged electronic connectors. The guidance targets how GD&T annotations should be associated with AP210 product representations across both mechanical and electrical design usage views, including 3D boundary representation and 2D footprint definitions. It also addresses connector vendor specifications, where mechanical details and PCB layout recommendations often include mounting and mating GD&T annotations. Building on earlier NIST work for packaged electronic components, it proposes representation methods for critical GD&T annotations in connector footprints and updates associations and relationships to support typical connectors with mounting features and through-hole terminals.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages22

Reading Time55 min

AccessFree to download

Introduction

Purpose and scope

Background on GD&T representation in STEP AP 210

Shape_element and geometry association concepts

NISTIR 7716 Recommended practice extensions for GD&T in STEP-AP210 in the context of electronic connectors Jamie Stori SFM Technology, Inc. Urbana, Illinois Kevin Brady National Institute of Standards and Technology Information Technology Laboratory -1- NISTIR 7716 Recommended practice extensions for GD&T in STEP-AP210 in the context of electronic connectors Jamie Stori SFM Technology, Inc. Urbana, Illinois Kevin Brady National Institute of Standards and Technology Information Technology Laboratory U.S. Department of Commerce John Bryson, Secretary National Institute of Standards and Technology Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technolog Recommended practice extensions for GD&Tin STEP-AP210 in the context of electronic connectors Introduction The purpose of this document is to extend the recommended practices for the representation of GD&T in STEP AP 210 (ISO-10303:210) in the context of packaged electronic connectors. Geometric dimensioning and tolerancing (GD&T) is critical to the design, manufacture, and assembly of electronic products. STEP AP 210 is unique in its ability to represent detailed usage views of electronic components spanning both the mechanical (MCAD) and electrical (ECAD) design domains. Within the STEP standards (ISO-10303), prior attention has been focused on the representation and presentation of GD&T in the context of three-dimensional (3D) boundary-representation (B-REP) models. In this context, GD&T annotations are typically associated with faces in the 3D model. Vendors of electro-mechanical components such as connectors typically provide detailed specifications ofthe mechanical properties of their components, and often will include a recommended PCB layout for the component. Both the mechanical specification and the PCB layout recommendation will often include GD&T annotations. This is particularly relevant in the context of mounting and mating features, such as mounting and alignment holes and features such as bosses, slots, and studs. Typically, the GD&T annotations are provided as a technical drawing, most often in .pdf format. An AP210 model ofan electronic component such as a connector will ideally contain both a detailed three-dimensional geometric representation, suitable for use in mechanical design, as well as a detailed two-dimensional footprint definition that supports the application of the component in PCB layout and PCA assembly. Existing implementations have validated the ability of AP210 to represent the detailed two and three-dimensional geometric models and product structure of a connector. A prior recommended practice document1, explored the population of GD&T annotations on a 3D geometric representation of a packaged electronic component represented in AP210 . This document extends that prior work in the context of connectors by proposing a recommended practice for the representation of critical GD&T annotations within the footprint definition of a component, and updating the recommended representation of certain associations and relationships. The concepts discussed will support the GD&T representation requirements ofa typical connector with a combination of both mounting features and through-hole terminals. Where relevant, elements of the prior recommended practice have been included in the current document. Many of the supporting details have not been repeated, however, and the prior document should be referenced as applicable. 1 Stori, J., Brady, K., and Thurman, T, 2009 “Extensions to the recommended practices for GD&T in STEP-AP210 in the context of packaged electronic components,” NISTIR 7634, [http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903904](http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903904) Shape_description_association Shape_element Geometric_model represented_characteristic representation Figure 1. Three mechanisms for associating geometry with a Shape_element sha

FAQs

What is the main purpose of NISTIR 7716?

To extend recommended practices for representing GD&T in STEP AP 210 for packaged electronic connectors, focusing on how GD&T annotations are represented and associated with the product geometry and footprint definitions.

Which STEP AP 210 contexts does the document address for connectors?

It covers connector representations spanning mechanical and electrical usage views, including both 3D boundary-representation models and 2D footprint definitions used for PCB layout and assembly.

How does the document relate GD&T annotations to AP210 geometry?

GD&T annotations are typically associated with elements in the AP210 model; the document explains that the Shape_element concept enables specific parts of a shape to be identified and linked as the critical link between GD&T annotations and the geometric model.

Oct 24, 2026

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