EPSG

EPSG is a widely used geodetic parameter dataset that provides standardized definitions for coordinate reference systems (CRS), datums, ellipsoids, and coordinate operations. Each entry is identified by a unique EPSG code and describes how geographic and projected coordinate systems are represented in GIS applications.

Originating with the European Petroleum Survey Group, the dataset is now maintained as the EPSG Geodetic Parameter Dataset by a collaborative effort within the international oil and gas community. The official repository and definitions are published on epsg.org, which serves as the primary reference for the dataset.

Entries cover geographic coordinate systems, projected coordinate systems, and coordinate operations that define transformations between CRS. Each record includes a name, datum, ellipsoid, projection method and parameters (for projected systems), area of use, units, and other metadata. The dataset also includes codes for coordinate operations and related geodetic components.

Usage and influence: EPSG codes are widely adopted by GIS software and libraries, including PROJ, GDAL, QGIS, and ArcGIS, to identify and transform CRS. This common reference supports data interoperability and reproducible analyses. Examples include WGS 84 (EPSG:4326) and NAD83 (EPSG:4269).

Access and updates: The dataset is freely accessible through epsg.org and distributed in formats such as XML, SQL, and CSV for integration into software. Updates add new projections, areas of use, and transformation methods.