ISO 14306-4:2026

Industrial automation systems and integration — JT file format specification for 3D visualization — Part 4: Version 3

This document defines the syntax and semantics of a file format for the 3D visualization and interrogation of lightweight geometry and product manufacturing information derived from CAD systems, using visualization software tools that do not need the full capability of a CAD system. This document has been adopted as a 3D visualization capability in addition to the ISO 10303 series. The ISO 10303 series are the ISO standards adopted for the engineering data exchange, sharing and long-term archiving of product definition information throughout the product lifecycle. In this document 3D visualization is defined as the visual presentation on a screen or another media of graphical and textual 3-dimensional representations of a set of data representing an object, information or results of a computational process in order to enable decision process by a human looking at the data visualized in a medium. The ISO 14306 file format specification for 3D visualization includes data descriptions that can represent the following data: facet information (triangles), stored with geometry compression techniques; visual attributes such as lights, textures and materials; product manufacturing information (PMI); boundary representation (b-rep) solid model shape representation and associated metadata; configuration representations; and delivery methods such as asynchronous streaming of content. The file format specification for 3D visualization does not specify the implementation of, or definition of a run-time architecture for viewing and/or processing ISO 14306 data.

Systèmes d'automatisation industrielle et intégration — Spécification de format de fichier JT pour visualisation 3D — Partie 4: Version 3

General Information

• Status: Published
• Publication Date: 06-Apr-2026
• ICS: 35.240.50 - IT applications in industry
• Technical Committee: ISO/TC 184/SC 4 - Industrial data
• Drafting Committee: ISO/TC 184/SC 4 - Industrial data
• Current Stage: 6060 - International Standard published
• Start Date: 07-Apr-2026
• Due Date: 31-Jan-2026
• Completion Date: 07-Apr-2026

Relations

• Revises: ISO 14306:2017 - Industrial automation systems and integration — JT file format specification for 3D visualization
• Effective Date: 07-Jan-2025

Overview

ISO/FDIS 14306-4 (ISO 14306-4 Version 3) defines the JT file format specification for 3D visualization. The standard specifies the sequential order of bytes that make up JT file segments used to represent 3D product data for high-performance, streamable visualization. It standardizes compressed JT content (now using LZMA compression) and data descriptions for geometry, visual attributes, metadata and delivery methods - while explicitly not prescribing any runtime viewer or processing architecture.

Key topics and technical requirements

• File structure and segments: Detailed definitions for file header, LSG (scene graph), Shape LOD, geometry segments, MetaData and new Info and Smart Topology Table (STT) segments.
• Geometry representations: Support for facet meshes (triangles) with geometry compression, B‑Rep (STEP and XT), wireframe and related topology constructs. Note: two lightweight representations (ULP and LWPA) are proposed for deprecation in this Part 4 specification.
• Visual attributes and materials: Definitions for lights, textures, materials and palette constructs (e.g., Palette Map Attribute Element, Sabot Attribute Element for forward compatibility). Material and surface attributes are supplied via a separate Reference Data Library.
• Product Manufacturing Information (PMI): Structured PMI support, including a complete list of PMI String Property Atom Element values provided as an electronic Reference Data Library; new PMI entity values (e.g., Weld Note Type 0x0309) and association reason codes.
• Compression and encoding: Adoption of LZMA for file compression; encoding algorithms, hash and data collection formats are specified.
• Conformance and conventions: Conformance classes, notational conventions, scene graph construction, late-loading data and metadata conventions are defined to ensure interoperable implementations.
• Normative/Informative annexes: Extensive annexes cover STEP B‑Rep, XT mapping, topology, coding algorithm examples, smart topology table, wireframe, and change history.

Applications and users

ISO 14306-4 is intended for organizations and professionals who create, exchange or consume JT 3D data:

• CAD/PLM and visualization software developers implementing JT import/export and streaming viewers.
• Manufacturing, automotive, aerospace and industrial engineering teams using lightweight, compressed 3D visualization for design review, digital mock-up and collaboration.
• System integrators and standards implementers building interoperable data pipelines and conformance test suites.
• Data architects defining PMI, metadata and reference libraries for enterprise reuse.

Related standards

• ISO 14306 series (other Parts 1–3) - consult the ISO website for the complete set.
• Industry JT format releases referenced (this edition is based on JT 10.5 requirements, updated from JT 9.5 in previous editions).

Keywords: JT file format, 3D visualization, ISO 14306-4 Version 3, LZMA compression, PMI, B‑Rep, scene graph, smart topology, reference data library, PLM, CAD.

Standards Content (Sample)

International
Standard
ISO 14306-4
First edition
Industrial automation systems
2026-04
and integration — JT file format
specification for 3D visualization —
Part 4:
Version 3
Systèmes d'automatisation industrielle et intégration —
Spécification de format de fichier JT pour visualisation 3D —
Partie 4: Version 3
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .vii
Introduction .ix
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions .2
3.2 Abbreviated terms .2
4 Notational conventions . 3
4.1 Diagrams and field descriptions .3
4.2 Data types .6
4.3 Empty field .8
5 File format . 9
5.1 General .9
5.2 Object types . .9
5.3 File structure .9
5.3.1 File header .10
5.3.2 TOC segment .11
5.3.3 Data segment . 12
5.4 Data segments .17
6 LSG segment .18
6.1 Segment overview .18
6.2 Graph elements .18
6.3 Node elements .19
6.3.1 Base node element .19
6.3.2 Base node data .19
6.3.3 Partition node element . 20
6.3.4 Group node element . 22
6.3.5 Instance node element . 23
6.3.6 Part node element .24
6.3.7 Metadata node element . 25
6.3.8 LOD node element. 25
6.3.9 Range LOD node element . 26
6.3.10 Switch node element .27
6.3.11 Base shape node element . 28
6.3.12 Vertex shape node element .31
6.3.13 Tri-strip set shape node element . .32
6.3.14 Polyline set shape node element .32
6.3.15 Point set shape node element . 33
6.3.16 Polygon set shape node element . 34
6.3.17 NULL shape node element . 34
6.3.18 Primitive set shape node element . 34
6.4 LSG attribute elements . 36
6.4.1 Material attribute element . 38
6.4.2 Texture image attribute element .42
6.4.3 Draw style attribute element . 54
6.4.4 Light set attribute element . 56
6.4.5 Linestyle attribute element .57
6.4.6 Pointstyle attribute element .59
6.4.7 Geometric transform attribute element . 60
6.4.8 Palette map attribute element .62
6.4.9 Infinite light attribute element . 63
6.4.10 Point light attribute element . 65
6.5 Property atom elements . 68

iii
6.5.1 Base property atom element . 68
6.5.2 String property atom element . 69
6.5.3 Integer property atom element .70
6.5.4 Floating point property atom element .70
6.5.5 JT object reference property atom element .71
6.5.6 Date property atom element . 72
6.5.7 Late loaded property atom element . 73
6.5.8 Vector4f Property atom element .74
6.6 Property table .74
7 Shape LOD segment . 76
7.1 Shape LOD segment overview .76
7.1.1 Tri-strip set shape LOD element .76
7.1.2 Polyline set shape LOD element . 77
7.1.3 Point set shape LOD element. 77
7.1.4 Polygon set LOD element . 78
7.1.5 Null shape LOD element . 89
7.1.6 Primitive set shape element . 89
8 Geometry segments .96
8.1 Geometry segments overview . 96
8.2 STEP B-Rep segment . 96
8.3 Wireframe segment. 96
8.4 XT B-Rep element . 97
9 MetaData segment . .97
9.1 MetaData segment overview . 97
9.2 Property proxy MetaData element . 97
9.3 PMI manager MetaData element . . 100
9.3.1 PMI design group entities . . . 101
9.3.2 PMI associations . 103
9.3.3 PMI user attributes . 105
9.3.4 PMI string table . 106
9.3.5 PMI model views . 107
9.3.6 Generic PMI entities. 109
9.3.7 PMI CAD tag data .119
9.3.8 PMI polygon data . 120
9.3.9 PMI model view sort orders . 123
9.3.10 PMI association properties . 123
9.3.11 Generic PMI additions . 125
10 Info segment . 128
11 Data compression and encoding .129
11.1 Data compression and encoding overview . 129
11.2 Common compression data collection formats . 130
11.2.1 Int32 compressed data packet . 130
11.2.2 Int64 compressed data packet . 135
11.2.3 Compressed vertex coordinate array . 137
11.2.4 Compressed vertex normal array. 138
11.2.5 Compressed vertex texture coordinate array . 140
11.2.6 Compressed vertex colour array .141
11.2.7 Compressed vertex flag array .143
11.2.8 Compressed auxiliary fields array .143
11.2.9 Point quantizer data .147
11.2.10 Texture quantizer data .147
11.2.11 Colour quantizer data . 148
11.2.12 Uniform quantizer data . 149
11.2.13 Compressed entity list for non-trivial knot vector . 149
11.2.14 Compressed control point weights data . 153
11.2.15 Compressed curve data . 153

iv
11.2.16 Compressed CAD Tag Data . 156
11.3 Encoding algorithms . 158
11.3.1 Uniform data quantization .158
11.3.2 Bitlength CODEC .158
11.3.3 Arithmetic CODEC . 159
11.3.4 Deering normal CODEC . 164
11.4 LZMA compression . 166
12 Conformance requirements .166
12.1 General conformance . 166
12.2 Conformance classes . 166
12.2.1 Approximated geometry visualization (CC01) .167
12.2.2 Precise geometry visualization (CC02) .167
13 Common data conventions and constructs .167
13.1 Overview .167
13.2 Late-loading data .167
13.3 TOC segment location .167
13.4 Bit fields .167
13.5 Empty field . 168
13.6 Hash value . . 168
13.7 Scene graph construction . 168
13.8 Metadata conventions . 169
13.8.1 Property key naming conventions . 169
13.8.2 PMI properties .170
13.8.3 CAD properties .171
13.8.4 Tessellation properties . 172
13.8.5 Miscellaneous properties . 173
13.8.6 The SUBNODE property and reference sets .174
13.8.7 Material and surface designation properties . 178
13.9 LSG attribute accumulation semantics . 178
13.10 LSG part structure . 179
13.11 Range LOD node alternative rep selection . 179
13.12 B-Rep face group associations . 180
13.13 Smart topology table (STT) segment . 180
13.14 Watermark image . 181
13.15 State flags . 181
Annex A (normative) Information object registration .182
Annex B (informative) Object type identifiers .183
Annex C (informative) Coding algorithms – An implementation .185
Annex D (informative) Hashing – An Implementation. 208
Annex E (informative) Polygon mesh topology coder .211
Annex F (informative) Per face group attributes .229
Annex G (normative) STEP B-Rep .233
Annex H (normative) STEP schema .236
Annex I (informative) XT B-Rep data segment .303
Annex J (informative) Smart topology table (STT) segment . 405
Annex K (normative) Wireframe segment .431
Annex L (informative) Mapping table 14306-4 XT B-Rep to STEP . 434
Annex M (informative) Procedural geometry – Evaluation and approximation .440
Annex N (normative) Information Object Registration Scheme .475
Annex O (informative) Change history .477

v
Bibliography .479

vi
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 184, Automation systems and integration,
Subcommittee SC 4, Industrial data.
This first edition of ISO 14306-4, together with ISO 14306-1, ISO 14306-2, ISO 14306-3, cancels and replaces
the second edition ISO 14306:2017, which has been technically revised.
The main changes are as follows:
— this document defines the requirements based upon the JT 10.5 file format requirements, whereas ISO
14306:2017 defines the requirements based upon the JT 9.5 file format requirements. A detailed list of
the changes are shown in Annex O;
— the version string in the File Header has been updated to reflect ISO 14306-4 Version 3;
— the file compression format has changed from Z-Lib to the publicly available LZMA format;
— the technical description for MbStrings Composite Data Types has been updated to include UTF 16;
— new segment types have been added for Smart Topology Table (STT) and Info Segment;
— the Base Attribute Data description has been expanded to include the logical collection Base Attribute
Data Fields V2;
— a new attribute element has been added to the LSG definition, Palette Map Attribute Element;
— a new attribute element, “Sabot Attribute Element”, has been added to the LSG definition. Sabot is used
to insulate earlier readers from attributes with non-fallback palette Index attributes in order to pre-
serve forward compatibility;
— new PMI Association values have been included to support partial scene sectioning;

vii
— a complete description of all PMI String Property Atom Element values is made available as a Reference
Data Library in electronic format;
— generic PMI Entity Type values have a new value; 0x0309 Weld Note Type;
— an Annex F (Per Face Group Attributes) has been added;
— two new PMI Associations Reason Code values have been added, code 256 and code 257;
— Annex I is related to the XT BREP geometry definition. The following changes have been made in
I.1.1.1.5
Updates in the “Topology” description.
Updates in the “World Topologies” table.
Updates to the “Body fields” table.
Updates to the “Region fields” table.
A list of all parts in the ISO 14306 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

viii
Introduction
The ISO 14306 format is an industry focused, high-performance, lightweight, flexible file format for capturing
and repurposing 3D product definition data for visualization to enable collaboration and validation
throughout the extended enterprise. The ISO 14306 format is streamable and contains compression for
compact and efficient representation.
Some of the highlights of the ISO 14306 format include:
— built-in support for assemblies, sub-assemblies and part constructs;
— flexible partitioning scheme, supporting single or multiple files;
— b-rep solid shape representations to provide precision to the light-weight viewing processes;
— product manufacturing information in support of paperless manufacturing initiatives;
— precise and imprecise wireframe shape representations;
— discrete purpose-built levels of detail;
— triangle sets, polygon sets, point sets, line sets and implicit primitive sets (such as cylinder, cone and
sphere);
— full array of visual attributes such as for materials, textures, lights;
— hierarchical bounding box and bounding spheres;
— data compression that allows producers of ISO 14306 files to fine tune the trade-off between compression
ratio and fidelity of the data.
Beyond the data contents description of the ISO 14306 format, the overall physical structure/organization of
the format is also designed to support operations such as:
— offline optimizations of the data contents, therefore file granularity and flexibility optimized to meet the
needs of enterprise data translation solutions;
— asynchronous streaming of content, therefore viewing optimizations;
— occlusion culling and fixed-framerate display modes;
— layers, and layer filters.
NOTE This document is based on the JT Open version 10.5 specification, which defines a logical scene graph with
geometry specific node and attribute support, extended to support the ISO 10303 series.
Annex A contains an identifier that conforms to ISO/IEC 8824-1. The identifier unambiguously identifies this
document in an open information system.
Annex A contains an identifier that conforms to ISO/IEC 8824-1. The identifier unambiguously identifies
this document and the schema in an open information system. The ISO 14306 series applies the method as
described in Annex N.
ix
International Standard ISO 14306-4:2026(en)
Industrial automation systems and integration — JT file
format specification for 3D visualization —
Part 4:
Version 3
1 Scope
This document defines the syntax and semantics of a file format for the 3D visualization and interrogation
of lightweight geometry and product manufacturing information derived from CAD systems, using
visualization software tools that do not need the full capability of a CAD system.
This document has been adopted as a 3D visualization capability in addition to the ISO 10303 series.
The ISO 10303 series are the ISO standards adopted for the engineering data exchange, sharing and long-
term archiving of product definition information throughout the product lifecycle.
In this document 3D visualization is defined as the visual presentation on a screen or another media of
graphical and textual 3-dimensional representations of a set of data representing an object, information
or results of a computational process in order to enable decision process by a human looking at the data
visualized in a medium.
The ISO 14306 file format specification for 3D visualization includes data descriptions that can represent
the following data:
— facet information (triangles), stored with geometry compression techniques;
— visual attributes such as lights, textures and materials;
— product manufacturing information (PMI);
— boundary representation (b-rep) solid model shape representation and associated metadata;
— configuration representations; and
— delivery methods such as asynchronous streaming of content.
The file format specification for 3D visualization does not specify the implementation of, or definition of a
run-time architecture for viewing and/or processing ISO 14306 data.
2 Normative references
ISO 10303-21:2016, Industrial automation systems and integration — Product data representation and
exchange — Part 21: Implementation methods: Clear text encoding of the exchange structure
ISO 10303-42:2024, Industrial automation systems and integration — Product data representation and
exchange — Part 42: Integrated generic resource: Geometric and topological representation
ISO 14306-2:2024, Industrial automation systems and integration — JT file format specification for 3D
visualization — Part 2: Vocabulary

3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14306-2 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
Abs absolute value
Bbox bounding box
B-Rep boundary representation
CAD computer aided design
CODEC coder-decoder
GD&T geometric dimensioning and tolerancing
GUID globally unique identifier
HSV hue, saturation, value
LCS local coordinate system
LsbFirst least significant byte first
LZMA Lempel–Ziv–Markov
Max maximum
MCS machine coordinate system
Min minimum
MsbFirst most significant byte first
N/A not applicable
PCS parameter coordinate space
PLM product lifecycle management
RGB red, green, blue
RGBA red, green, blue, alpha
TOC table of contents
VPCS viewpoint coordinate system

URL uniform resource locator
WCS world coordinate system
4 Notational conventions
4.1 Diagrams and field descriptions
Symbolic diagrams are used to describe the structure of the ISO 14306 file. The symbols used in these
diagrams are shown in Table 1 and have the following meaning:
Table 1 — Symbols
Symbol Description
Rectangles represent a data field of one of the standard data types.
Folders represent a logical collection of one or more of the standard data types. This infor-
mation is grouped for clarity and the basic data types that compose the group are detailed
in following sections of the document.
Rectangles with extra lines at left and the right sides corners clipped off represent informa-
tion logical steps that has been compressed.
Rectangles with the right side corners clipped off represent information that has been
compressed.
Arrows convey the ordering of the information.
The format used to title the diagram symbols is dependent upon the symbol type as follows:
Diagram “rectangle box” (therefore, standard data types) symbols are titled using a format of “Data_Type :
Field_Name.” The Data_Type is an abbreviated data type symbol as defined in 3.2 data types. In the example
shown in Figure 1 the Data_Type is “I32” (a signed 32 bit integer) and Field_Name is “Count.”
Figure 1 — Rectangle box diagram
Diagram “folder” (therefore, logical data collections) symbols are simply titled with a collection name. In the
example shown in Figure 2 the collection name is “Graph Elements.”
Figure 2 — Folder diagram
Diagram “rectangle box with lines at left and right sides” are simply titled with a logic step name. In the
example shown in Figure 3 the logic step name is “Recover First Shell Indices”.
Figure 3 — Rectangle box with lines at left and right sides diagram
Diagram “rectangle box with clipped right side corners” (therefore, compressed/encoded data fields) are
titled using one of the following three formats:
...