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Monday, 2017-12-11

LOTAR 3D CAD with PMI Workgroup

Goals and Objectives

The specific goal of the 3D Mechanical & PMI Technical Working Group is focused on the preservation of the explicit 3D Geometric shape representation and associated Product and Manufacturing Information. The results will be documented as NAS/EN 9300-1xx parts. ( See table below )

Mechanical Domain: Parts 100, 110, 115

Goals and Objectives

The 3D Mechanic Domain covers the definition of the physical shape of a component, the positioning of components within an assembly, and the information about shape, such as tolerances or surface finish, which constrains the results of a manufacturing process, but does not specify the process itself.

The Domain also covers the ‘explicit representation’ which refers to the mathematical representation of the final result of the CAD model. From the designer's point of view, it corresponds to the 3D shape (points, curves, surfaces, solids etc.). Explicit 3D shape may be associated with non-geometric data including design management meta-data such as layer, color or group or user defined properties. These non-geometric data are optional, and are added by users and checked and validated by specific tools.

The 3D Mechanical Domain finally describes the requirements, and particularly the information required, for the long term archiving and retrieval of a mechanical CAD explicit assembly structure.  This will allow the retrieval of the assembly structure including the placement information.

PMI Domain: Parts 120, 121, 122, 125

Goals and Objectives

The objective of the Product and Manufacturing Information (PMI) Domain, is to define the requirements for the long term digital preservation of the presentation of Product and Manufacturing Information (PMI) with their associativity to the 3D explicit shape and geometry of CAD parts. 

The specific Goal of the PMI Working Group is focused on the preservation of the explicit 3D Geometric shape representation and associated Product and Manufacturing Information.

There are different levels of information that can be exchanged in that context, which are listed below:


The 3D Mechanical PMI team in support of Industry's requirements to have an explicit 3D Geometric Shape Representation with associative 3D Product & Manufacturing Information presented in an ISO 10303 AP 203, AP 214, or AP242 file format in a timely manner. Options were to use current enabling technology to support this requirement and to develop the geometric based parts P100, 110 and 115 and phase in the PMI aspects as technology matured as described below.

  • Phase I: The PMI would be represented graphically with cross-highlighting capability. The PMI would be initially presented as non-semantic Polylines and documented in EN/NAS 9300-120e1. Edition 2 would present the PMI as Tessellated entities.

  • Phase II: The PMI would be represented as semantic STEP entities that are fully associative to the Geometric Shape Topology. This would be documented in EN/NAS 9300-121 aligned with AP242.

  • Phase III: Will include explicit 3D Geometric Shape Representation with associative 3D PMI applied to Form Features with the addition of Parametric constructs all supported by a single STEP file. This would be documented in EN/NAS 9300-122.

  • As Parts 120 through 122 address detailed part types, Part 125 will focus on 3D Geometric Assembly Representations with associative PMI constructs. The Part 125 work referenced the work accomplished in the AP242 External Element Reference team as a baseline.

Figure 3 describes a generic process of development of 3D CAD parts with PMI illustrating the main categories of essential information to be created in the Aerospace and Defense industry. The associated tasks for developing, manufacturing and supporting 3D CAD parts with PMI are also illustrated.  The current priorities of development of the LOTAR 1XX standards are also shown.

Associated LOTAR use cases

The LOTAR standards 1XX family will address the following use cases (in development).

# Title Status
1 L-T Archiving and Retrieval of CAD 3D exact geometry with PMI Complete
2 L-T Archiving and Retrieval of CAD 3D exact geometry, assembly level PMI Draft

The LOTAR Family of Standards for 3D CAD PMI

The planned NAS / EN 9300-1XX standards for the Long Term Preservation of 3D CAD Geometry with Product & Manufacturing Information (PMI) include the following:

Part Title Status
100 Common concepts for L-T Archiving and retrieval of CAD 3D mechanical information Rel 2012
110 L-T Archiving and Retrieval of CAD mechanical 3D Explicit geometry information Rel 2012
115 Explicit CAD assembly structure Rel 2012
120 Long Term Archiving & Retrieval of CAD 3D Explicit Geometry with Graphic PMI Presentation Rel 2013
121 Long Term Archiving & Retrieval of CAD 3D Explicit Geometry with Semantic PMI Representation Draft
122 Long Term Archiving & Retrieval of CAD 3D Explicit Geometry with Machining Form Features TBS
125 Long Term Archiving & Retrieval of CAD 3D Assemblies with Graphic PMI Presentation Draft

Associated ISO 10303 Information Models

  • The LOTAR standards do not define specific information models for Long Term preservation of CAD and PDM information models. They rely closely on the ISO 10303 STEP Application Protocols. The STEP modular architecture ensures the consistency of the information models subsets common to several ISO 10303 standards.

  • The LOTAR P1XX family is based on:  
    • ISO 10303-203 “Configuration-controlled design”
    • ISO 10303 -214 “Automotive Design”
    • ISO 10303-42 “Product data representation and exchange”
    • ISO 10303-47 “Shape Variation Tolerances”
    • ISO 10303-59 “Quality of Product Shape Data”
    • ISO 10303-519 “Geometric Tolerance” this AIC describes the PMI model used in P120
    • ISO 10303-242 “Managed Model Based 3D Engineering”


  • The 3D Mechanical PMI Working Group Part110e2/P120e2/P121e1 holds bi-weekly WebEx/Teleconf meetings on Tuesdays from 08:00am – 09:00am (PST)

  • The PMI Assembly Working Group P125e1 holds bi-weekly WebEx/Teleconf meetings on alternating Tuesdays from 08:00am – 09:00am (PST)


  • The PMI Working Group developed and implemented a Test Model Library consisting of 4 categories of test models which are all the same models developed natively in Dassault Systemes CATIA V5, Siemens NX, and PTC Creo. This will enable the testing community to evaluate errors to the exact geometric representation it was created in. We also have use of a series of test models that has been developed by NIST which are available at the following website:

The Categories are:

1. Atomic - contain a single PMI constuct depicting a specific value per ASME or ISO

2. Intermediate -contain multiple PMI constructs ranging from 2 - 5

3. Complex - contain multiple PMI constructs from 6 and larger, with the additon
                     of complex PMI configurations.

4. Assemblies - contain assembly PMI constructs  

  • The PMI Working developed and submitted EN/NAS 9300—100e1, 110e1, 115e1 and 120e1 for publication to AIA and ASD-STAN. These document are currently published.

  • The PMI WG is continuing work on Parts 110e2, 121e1 and 125e1 and have varying completion dates set in 2015.