What is a GMM file? A GMM file is an XML-formatted text file used to create .BMG files, which are binary files that contain the dialog and message text shown in various Nintendo video games. Most gamers will never encounter GMM files, but those who do can open, examine, and edit them in any text editor.

More Information Nintendo video games include many files created and saved in a variety of proprietary file formats. To create files that contain a game's dialog and other in-game text, Nintendo developers use a program called Message Editor. Developers use Message Editor to save some games' in-game text in BMG files. These files are binary files that contain the final version of a game's text. Before developers create a BMG file, they first edit and save the game's text in a GMM file. The GMM file is an XML-formatted text file that developers can open and edit in Message Editor. Because GMM files are primarily used by Nintendo developers, most gamers will not encounter them. However, some enterprising gamers have used a game's GMM file to help them translate the game's in-game text. For example, MapleStory: The Girl of Destiny players used that game's GMM file in their efforts to create an English version of the game.