4 file types use the .gml file extension.

What is a GML file?

Developer file used by GameMaker, a program used to create computer video games; contains program code written in the GameMaker Language (GML) that is executed by the GameMaker interpreter.

More Information

Category: Developer Files

Geography Markup Language File

A GML file contains Geography Markup Language (GML), which is a language that includes XML-like tags defining geographic attributes and geometry coordinates. GML is an open, interchangeable format that geographers use to model geographical features, such as roads, lakes, and rivers, in Geographic Information Systems ( GIS ). GML files may also use the .xml file extension ( .XML files).

Galdos Systems initially released GML in 2000, basing it on the Resource Description Framework ( RDF ). However, the Open Geospatial Consortium (OGC) soon took over the development of the format and introduced XML schemas (typically stored in .XSD files) to better connect the data in the many existing geographic databases.

Unfortunately, due to the varied use of GIS data (e.g., evaluating aviation weather, analyzing soil and terrain, vehicular navigation, etc.), different communities and organizations developed many incompatible schemas for defining GML files. Therefore, GML has diminished in favor of other, more interchangeable formats, such as .GEOJSON and .GPKG .

NOTE: You can find more information about GML on the Open Geospatial Consortium website ( ogc.org ).

You can open GML files with various GIS applications, including QGIS, TatukGIS Viewer , and Merkaartor . For example, to open a GML file with QGIS, click the Data Source Manager icon in the toolbar, select the Browse (...) button in the Source section, choose the GML file, and click Open .

Since GML files store plain text, you can also open them with a text or source code editor, such as Microsoft Visual Studio Code , Microsoft Notepad or Apple TextEdit .

Programs that open GML files

Updated: October 31, 2023

Gerber Mill Layer File

A GML file may also be a data output file created by Printed Circuit Board ( PCB ) CAD tools such as Autodesk EAGLE. It contains layout data for the layer that specifies the hole locations that need to be milled.

Gerber layer files, such as GML, are used by PCB manufacturing machines to create PCB boards. The GML file is an exported version of the PCB layout and is referenced to mill holes in the board.

NOTE: The Gerber format was originally developed by Gerber Systems but is now maintained by Ucamco.

[projectname].gml - The GML file is named after the name of your PCB project.

Programs that open GML files

Updated: July 20, 2017

Graph Modeling Language File

File created in the GML (Graph Modeling Language) format, an ASCII text format used for describing graph structures; describes the structure of the graph in a text-based hierarchy and includes the nodes, edges, and attributes that comprise the graph.

The Graph Modeling Language can describe family trees, flowcharts, networks, and other graph structures.

Programs that open GML files

Updated: September 25, 2014