Save file using different extensions in MS Word

Usually, MS Word will append a fixed extension for a given file type. If you want to use a different extension, you need to enclose the file name in quotes. For example, "textfile.dat" will force MS Word to use dat as extension.

Open a file by drag-and-drop in MS Word

Unlike many other editors, for MSWord, the file should be dropped in the menu area.
It should not be dropped in document area. If it's dropped in document area,
it will become an embedded file.