The _DOCX file extension was developed by Microsoft. This file format is used for temporary files that are created by MS Word 2007. The ._docx file format is also used by later versions of MS Word, specifically those with support for opening, creating and editing DOCX files. Temporary files in the _DOCX format correspond to specific DOCX files. These temporary files are normally saved by MS Word in the same directory where the associated DOCX file is stored. Usually visible when the associated DOCX file is open, these _DOCX files contain autosaved data. These _DOCX files are deleted by MS Word once a user saves all changes made to the associated DOCX file, or once the user chooses to discard the autosaved changes. MS Word use these _DOCX files when users want to recover their most recent edits to a DOCX file that was abruptly closed due to a system or program crash. It's best to leave these _DOCX files alone, in order for MS Word to be able to recover autosaved changes done to prematurely closed DOCX files.
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