FM file is used by Adobe FrameMaker software application. The application uses FM file as the main document file which will store the information related to the data added in the document by the user.

The structured documents which are added in the single file are compiled in this FM document file. This file can be used as a final compiled document which is ready for distribution. The document file is saved as text based format and the only thing which can vary in the file data is the information of structure of elements which are added in the file. If the file is structured there is additional information added in the document file.