# STEP AP242

Exchanging product geometry, assemblies and manufacturing information with explicit edition and translator boundaries.

Reviewed: 2026-11-01

Tags: parts-and-design, file-formats, step, interoperability

## Identity and edition

Specify AP242 edition, geometry representation and required manufacturing information. The reviewed **ISO 10303-242:2025**, edition 4 (August 2025), replaces the 2022 edition. ISO lists a successor committee draft in development. [ISO AP242 edition and scope](https://www.iso.org/standard/84300.html)

Product and manufacturing information can have two distinct roles. NIST distinguishes **semantic PMI**, which represents requirements in computer-interpretable form, from **graphical PMI**, which preserves an annotation's visible appearance. A displayed tolerance frame is not proof that software can query its meaning. [NIST PMI definitions](https://www.nist.gov/services-resources/software/step-file-analyzer-and-viewer)

A STEP Part 21 exchange file commonly uses `.stp`, `.step` or `.p21`. These extensions are also used with other application protocols, including AP203 and AP214. An extension is consequently insufficient evidence that a delivery is AP242 or contains PMI. Identify the schema and inspect the imported content. [NIST STEP File Analyzer and Viewer](https://www.nist.gov/services-resources/software/step-file-analyzer-and-viewer)

Treat an exchange requirement as a combination of application protocol, edition, geometry representation, required information and receiving software. A file that opens successfully may still omit the information needed to program inspection, identify assembly occurrences or interpret a tolerance.

## Geometry and product structure

AP242's standard scope extends beyond a single solid: it includes parts, assemblies, product properties, configuration information and annotated product documentation. These are format capabilities, not a promise that every exporter writes them or every importer restores them. A tessellated representation useful for visualization is a different deliverable from boundary geometry required by a particular CAD or CAM workflow. Specify the required representation rather than relying on the phrase “3D STEP.” [ISO scope](https://www.iso.org/standard/84300.html)

For a practical handoff, state whether the recipient needs individual parts, an assembly hierarchy, repeated occurrences, component names and placements. Inspect both the structure and the positioned geometry after import. A visually correct assembly does not establish that separate occurrences or their identities survived. Likewise, a usable imported solid does not demonstrate restoration of the source application's editable feature history. These are acceptance questions to agree with the recipient, rather than universal AP242 guarantees.

## Semantic PMI versus graphical PMI

| Required outcome | What to examine after import |
| --- | --- |
| A person can read the annotation | Symbols, text, placement, orientation and saved views |
| Software can interpret the requirement | Structured dimension or tolerance data, datum information and applicable geometry associations |
| A reviewer can identify the controlled feature | Annotation attachments and references, not just proximity on screen |

PTC's Creo 12 documentation illustrates why implementation details matter. It describes preservation of annotation views, names, colors and geometric references, but also requires conversion of legacy annotations for specified AP242 exchanges. Its explicit note says that the `ap242` and `ap242_e3` protocols do not support import/export of assembly-level annotations. Do not transfer a part-level PMI success to assembly-level PMI without checking the selected protocol. [Creo 12 annotation exchange](https://support.ptc.com/help/creo/creo_pma/r12/usascii/data_exchange/interface/About_Exchanging_Graphical_Semantic_Annotate.html)

An automated inspection workflow should test the actual requirement types it consumes. Include representative datums, tolerance modifiers, dimensions and associations in a small exchange trial. Looking at a screenshot establishes presentation; querying the imported requirements establishes a different capability.

## Named implementation example

SOLIDWORKS 2026's **Publish to STEP 242** documentation lists export edition choices **1.0, 2.0 and 3.0** for parts and assemblies. It also exposes options for custom properties, splitting periodic faces and exporting face/edge properties. This is a specific documented exporter interface, not evidence that every SOLIDWORKS installation exports the latest ISO edition or that a receiver consumes every selected property. [SOLIDWORKS 2026 Publish to STEP 242](https://help.solidworks.com/2026/english/SolidWorks/sldworks/r_publish_step242.htm?id=19.6.5)

Record the actual CAD release, export edition and selected options when investigating an exchange problem. If a receiving system requires an older supported edition, agree that edition explicitly. Selecting the newest available setting is useful only when both systems support the required content in that setting.

## Validation and a bounded calculation

NIST's analyzer reports entities and attributes, examines PMI and validation properties against recommended practices, and checks basic file-format errors. Validation properties are quantities computed in the source CAD system for comparison after import. These checks help diagnose an exchange; they do not establish that the engineering definition is complete or that a part meets its design requirements. [NIST analysis capabilities](https://www.nist.gov/services-resources/software/step-file-analyzer-and-viewer)

**Original arithmetic example:** suppose the source reports a solid volume of 100,000 mm³ and the receiver reports 100,010 mm³. Using the source as the reference:

`relative volume difference = |100,010 − 100,000| / 100,000 × 100 = 0.01%`

This is a comparison result, not an acceptance threshold. The parties must establish a justified tolerance for their application. Equal volume alone cannot establish equivalent geometry: moving a hole within an otherwise unchanged part can preserve removed volume while changing its location. Check critical dimensions and features as well as aggregate quantities. Use consistent units and the same included bodies when comparing results; otherwise the calculation answers a different question.

For an assembly, also inspect component count, occurrence placement and any suppressed or excluded content. For manufacturing use, inspect small features and surfaces relevant to the planned operation. For PMI use, verify that required annotations are present, correctly attached and interpretable by the receiving application.

## Handoff decisions

A useful exchange request states the authoritative revision, AP242 edition, intended receiving application and required geometry/PMI content. Identify whether the STEP model or an accompanying drawing governs each requirement, and resolve disagreement before manufacture. Keep the exported file associated with its source revision; a neutral file name alone does not resolve configuration authority.

The recipient should confirm the features actually required for its task: editable geometry for modification, usable geometry for CAM, readable annotations for review or semantic requirements for automation. These are separate outcomes. A successful trial using the intended exporter, importer and representative content is more informative than a generic claim of “AP242 support.”

## Source versions and related reference

Sources checked on the review date include ISO 10303-242:2025 edition 4; SOLIDWORKS 2026 online help; Creo 12 online help; and NIST's STEP File Analyzer page, whose displayed update date is December 31, 2025. The software examples describe those documented releases and should be rechecked when translators change. [ISO](https://www.iso.org/standard/84300.html), [SOLIDWORKS](https://help.solidworks.com/2026/english/SolidWorks/sldworks/r_publish_step242.htm?id=19.6.5), [PTC](https://support.ptc.com/help/creo/creo_pma/r12/usascii/data_exchange/interface/About_Exchanging_Graphical_Semantic_Annotate.html), [NIST](https://www.nist.gov/services-resources/software/step-file-analyzer-and-viewer)

[Drawing and model file references](index.md)