Open DOC1 File
The DOC1 extension is a manually modified extension of Microsoft Word office
document.
This means that it is not a standard extension and to obtain it you must
do a manual modification of the original DOCX extension.
In any case, when making this modification, the original extension does not lose its format and once the name has been changed, you must associate the DOC1 extension with the Word or LibreOffice Writer program.
Thus, DOC1 would become the extension of the new format with which Microsoft Word 2007 saves files by default, replacing the well-known doc, since it is basically a DOCX extension.
Before the 2007 Office release, Word documents were saved as a DOC file. Starting with this version, Word uses the XML-based DOCX file format by default.
Compared to DOC, a DOCX (DOC1) file is a kind of compressed folder where most of the XML files are stored with the different sub-formats of the DOCX document.
If you are using an older version of Word, you will not be able to open DOCX (DOC1) files directly, but you will have to convert DOCX to DOC or install new programs in order to read DOCX.
To open and operate a DOC1 file, you must have one of the following programs installed, and correctly associate the DOC1 extension to them: