# JT files JT exchange: tessellation, precise geometry, PMI, assembly dependencies and version-specific handoff checks. Reviewed: 2026-11-01 Tags: parts-and-design, file-formats, jt, cad ## Identity and intended use Specify whether the JT delivery is for visual review, precise geometry or machine-readable manufacturing information. [Siemens: JT file format](https://www.siemens.com/en-us/products/plm-components/jt/) PTC's Creo 12 documentation makes the distinction explicit: default graphical annotations do not preserve PMI references. Its semantic export workflow calls for **As Is and Tessellated** plus **Rich content** under Annotations; its semantic import workflow uses the Geometry import type. The page also lists unsupported semantic dimension categories, including ordinate and driving dimensions, which are processed graphically. These are Creo-specific requirements and limitations. [PTC: exchanging PMI between JT and Creo](https://support.ptc.com/help/creo/creo_pma/r12/usascii/data_exchange/interface/Exchanging_PMI_Data_Between_JT_and_Creo.html) Keep that purpose separate from the authoring CAD model. An exchange suitable for visual review may omit information required for machining, inspection or subsequent design changes. Retain the authoritative design revision and identify which drawing, model or specification controls acceptance. A recipient opening the file successfully establishes readability, not completeness for the proposed operation. ## Versions and standards The current ISO family is multipart. ISO 14306-1:2024, published **August 2024**, gives the overview and fundamental principles. ISO 14306-3:2025, published **June 2025**, specifies **Version 2**; ISO 14306-4:2026, published **April 2026**, specifies **Version 3**. Their public descriptions concern visualization and interrogation of geometry and product manufacturing information derived from CAD. They do not prescribe a viewer's runtime implementation. [ISO Part 1](https://www.iso.org/standard/86063.html), [ISO Part 3](https://www.iso.org/standard/89233.html), [ISO Part 4](https://www.iso.org/standard/86064.html) Siemens separately advertises a JT file-format reference **V10.6** through its JT Open Program. Do not equate an ISO part's Version 2 or Version 3 with a Siemens 10.x number without the applicable specification and implementation mapping. Agree the actual export version supported by the receiving product and release. [Siemens: JT Open Program](https://www.siemens.com/en-gb/products/plm-components/jt/jt-open-program/) Record exporter, translator and receiver versions along with the saved format. Converting to an older version can solve one compatibility problem while changing available content. Review the converted result against the requirements rather than inferring preservation from the selected version alone. ## Facets, precise geometry and measurement Siemens' JT Open Toolkit supports multiple tessellated levels of detail, or LODs, and precise geometry through embedded Parasolid XT boundary representation. It also describes associations between geometry, facets and manufacturing information. These are supported capabilities; they are not a statement that every JT delivery contains all representations. [Siemens: JT Open Toolkit](https://www.siemens.com/en-us/products/plm-components/jt/jt-open-toolkit/) For **Creo Parametric 12**, PTC documents facet exchange as the default and an export choice for exact representations. It warns against selecting the Facet import type when exact geometry is required. This is a concrete example of why the same extension can lead to different imported content. [PTC: importing and exporting JT](https://support.ptc.com/help/creo/creo_pma/r12/usascii/data_exchange/interface/About_Importing_Exporting_JT_Visualization_Format.html) Before relying on a measured feature, establish whether the application is querying precise geometry, an analytic parameter or facets. A displayed dimension with many decimal places does not identify that representation or establish its accuracy. Compare critical features with the source model and the agreed translation tolerance. For manufacturing, determine whether the downstream tool accepts the delivered representation directly or performs another conversion. PTC's Creo 12 configuration guidance defines chordal control in terms of deviation from the approximated curve and provides angular and segment-length controls. It permits up to three LODs in that export workflow; this is an application limit, not a universal JT limit. Its external `jt.config` settings override export-profile options when enabled. Capture the effective configuration, not merely the visible profile name. [PTC: JT configuration options](https://support.ptc.com/help/creo/creo_pma/r12/usascii/data_exchange/interface/Exporting_Levels_of_Detail_LODs_to_JT.html) **Original geometric illustration:** approximating a circular arc of radius 10 mm with a straight chord spanning 20° gives a midpoint deviation of `10 × (1 − cos 10°) ≈ 0.152 mm`. This calculation demonstrates the potential difference between a curve and its polygonal approximation. It is not a JT default, an exporter setting recommendation or a guaranteed error bound for a delivered model. Inspect the relevant representation and its actual export controls. ## PMI: visible text versus usable relationships Product manufacturing information can include dimensions and tolerances. Siemens describes graphical and semantic PMI representations, with supported applications able to use the information as live data. Visible annotation graphics and machine-interpretable relationships should therefore be checked separately. [Siemens: PMI support](https://www.siemens.com/en-us/products/plm-components/jt/jt-open-toolkit/) When an inspection or manufacturing workflow needs semantic PMI, inspect references to the intended faces, edges or datums after import. Check values, symbols and annotation visibility as well. A screenshot can help compare presentation, but cannot establish that a datum relationship remains queryable. Resolve missing or downgraded information before releasing the exchange for that use. ## Assemblies and delivery packaging **Inventor 2026** documents three assembly export structures: MONOLITHIC stores the assembly in one JT file; PER PART stores the hierarchy in one file with part files in a subdirectory; FULL SHATTER stores each assembly component in a separate JT file. Its exporter also offers B-rep/facet choices and version selection; JT B-rep is unavailable for selected versions 10.3 and above in that implementation. Do not generalize those controls to other exporters. [Autodesk: JT export options](https://help.autodesk.com/cloudhelp/2026/ENU/Inventor-Help/files/GUID-68FCAD0E-93BD-4D90-B9FE-9CF82AA4E64D.htm) For a multiple-file delivery, preserve the exported directory relationships and test the package from its delivery location. Sending only the top-level file is insufficient if its referenced components are required. Compare instance counts, positions, orientations and the intended assembly configuration with the source. Distinguish repeated component instances from unique part definitions when reporting quantities. ## Practical acceptance record Use a short exchange record containing: - Part or assembly identifier, revision and intended use. - Authoring application, translator, saved JT version and receiving application release. - Required geometry representation, effective tessellation settings and PMI requirements. - Expected units, a known check dimension, orientation, assembly configuration and instance count. - All required component files, plus the authoritative dimensional and manufacturing requirements. Reopen the delivered package in the actual receiving workflow. Measure the known feature, inspect critical surfaces, verify assembly placement and query any required semantic annotations. Keep an original delivery alongside repaired or converted derivatives, with the change identified. These are proposed acceptance checks, not a claim that one viewer or translator certifies manufacturing suitability. ## Source scope and related reference The ISO dates above are publication dates from the standards records. Application examples are explicitly scoped to Creo 12 and Inventor 2026 documentation; no technical revision date is inferred from a crawl date. Siemens' live product pages establish advertised capabilities and the V10.6 reference listing, not universal installed-software support. See [Drawing and model file references](index.md) for the surrounding design handoff.