Guidance Notes

EPSG Dataset Supporting Documentation

IOGP Reports 373-07-01 through 373-07-06 form a multi-part document for users of the EPSG Dataset:

IOGP Report 373-07-01 (EPSG Guidance Note 7-1) – Understanding the EPSG Dataset, sets out detailed information about the Dataset content and its maintenance.

IOGP Report 373-07-02 (EPSG Guidance Note 7-2) – Coordinate conversions and transformations including formulas, provides a detailed explanation of formulas necessary for executing coordinate conversions and transformations using the coordinate operation methods supported in the EPSG Dataset. Geodetic parameters in the EPSG Dataset are consistent with these formulas.

IOGP Report 373-07-03 (EPSG Guidance Note 7-3) – EPSG Registry API user guide, is primarily intended to assist computer application developers who wish to use the RESTful API of the EPSG Registry to query and retrieve entities and attributes from the Dataset.

IOGP Report 373-07-04 (EPSG Guidance Note 7-4) – EPSG Database and SQL Script user guide, provides guidance for users of the EPSG Database and SQL scripts which may be obtained from the EPSG Registry Download Dataset page.

IOGP Report 373-07-05 (EPSG Guidance Note 7-5) – EPSG null and copy transformations to WGS 84, explains aspects of the policies for the inclusion in the EPSG Dataset of datum ensembles and so-called null coordinate transformations to WGS 84, including limitations in the description of WGS 84 through code EPSG:4326.

IOGP Report 373-07-06 (EPSG Guidance Note 7-6) – EPSG Dataset - Policies and procedures for data management, documents strategy for populating the EPSG Dataset.

The complete texts may be found in the Download section of this page.

Geomatics guidance notes

For all IOGP's Geomatics Committee reports, please go to IOGP Bookstore.

Download:

Guidance Note 7-1 (ver 9, Mar 2025)  
Guidance Note 7-2 (ver 71, Aug 2025)  
Guidance Note 7-3 (ver 1.0, Jul 2022) 
Guidance Note 7-4 (ver 4, Apr 2009)  New updated version coming soon
Guidance Note 7-5 (ver 1.1, May 2022) 
Guidance Note 7-6 (ver 1.1, Jun 2025) 

For an overview to the model changes see here.

From Geodesy Subcommittee

Raise awareness about geodetic integrity
Geodetic awareness is essential for operational decision making and to avoid HSE risk because: 1 - Most data have locations; 2 - Decisions and safe operations rely on the correctness of these locations; 3 - Coordinates are meaningless without a Coordinate Reference System (CRS).
For further information see geodetic awareness site and IOGP Report 373-01 Geodetic Awareness.

Dynamic Coordinate Reference Systems
Following the release of updated IOGP Report 373-25 Dynamic versus static CRSs and use of the ITRF, the Geomatics Committee has produced a video introducing the concept of dynamic coordinate reference systems. 
The video is shared under the same T&C as other IOGP Publications and can be reproduced in whole or in part provided (i) that the copyright of IOGP and (ii) the sources are acknowledged.