Know about the FrameMaker file extensions .fm, .mif, .book, .xml, .dita, .ditamap.
When you save a file for the first time in Windows, FrameMaker automatically adds these extensions:
.fm for FrameMaker documents
.mif for FrameMaker MIF (Maker Interchange Format) documents
.book for FrameMaker book documents
.xml/.dita for XML documents
.ditamap for DITA map and bookmap files
With these extensions, the files are recognized as FrameMaker files by the Windows operating system.
If you don’t want these special extensions added to the filenames you assign, enclose the filenames in double quotation marks. Windows doesn’t recognize a file without one of these extensions as a FrameMaker file, but you can still open the file in FrameMaker.
If you assign an extension that’s registered by another application, such as .doc or .docx, the extension is not replaced by the FrameMaker extension and you can still open the file in FrameMaker.