Windows 3.11 Program Group File Extension

In Microsoft Windows 3.11, the file extension used for program group files was .GRP. This article provides a concise overview of what .GRP files were, their function within the Windows Program Manager interface, and how they handled application shortcuts before being superseded by modern directory structures in later operating systems.

In Windows 3.11—as well as Windows 3.0, 3.1, and Windows NT 3.x—the default graphical shell was the Program Manager (PROGMAN.EXE). Rather than using traditional folders to store application shortcuts on a desktop or in a Start menu, Program Manager organized software into individual windows known as "Program Groups." Each of these groups was saved directly to the disk as a standalone .GRP file (such as MAIN.GRP or ACCESSOR.GRP), typically located in the C:\WINDOWS directory.

A .GRP file was a proprietary binary file format containing metadata rather than the executable programs themselves. It stored the spatial layout of the group window, the names of the application items, the paths to their respective executable files, custom working directories, and references to the icons displayed for each program. When a user created a new program group or added an icon within Program Manager, Windows updated or generated the corresponding .GRP file automatically.

Default program groups shipped with Windows 3.11 included Main (MAIN.GRP), Accessories (ACCESSOR.GRP), Games (GAMES.GRP), and StartUp (STARTUP.GRP). The list of active group files to load at boot was maintained inside the PROGMAN.INI configuration file under the [Groups] section.

The .GRP format became largely obsolete with the release of Windows 95, which replaced Program Manager with Windows Explorer, the Taskbar, and the Start menu. In Windows 95 and subsequent versions, program shortcuts were converted to individual .LNK files stored within nested file system directories.