The brstmspm file extension is related to the XWE editing tool for Windows.
What is brstmspm file? How to open brstmspm files?
The brstmspm file extension is associated with the XWE (also known as eXtendable Wad Editor) a software tool for Microsoft Windows that allows users to edit Doom WAD files.
The brstmspm file stores some kind of data used by XWE.
XWE allows users to view and edit sprites, textures, flats, sounds, SOCs, level headers, and any other type of lump included in WAD file.
and possible program actions that can be done with the file: like open brstmspm file, edit brstmspm file, convert brstmspm file, view brstmspm file, play brstmspm file etc. (if exist software for corresponding action in File-Extensions.org's database).
Click on the software link for more information about XWE. XWE uses brstmspm file type for its internal purposes and/or also by different way than common edit or open file actions (eg. to install/execute/support an application itself, to store application or user data, configure program etc.).