Today I downloaded a 2006-ish C++ teacher's guide saved using the .sxw file format.
The format shows OpenOffice.org 1.0 text document, in Caja file manager [Ubuntu MATE].
I remember using OOo 1.x and the only issues were not MS Office 97-2003 formats were not supported. I loved it when I was able to read/write .doc files, since I was transitioning from Windows to Linux and MSO 2003 to a free open-source office suite.
Today was the first time in 7 or 8 years that I had to open a .sxw file. Thank goodness LO still have support with those file formats. MSO no longer supports their early file formats, so I had to make sure I re-saved all my early Word, WordPerfect, etc. documents to the more "modern" formats [Word 95 floppy era].
I never thought I would find/download .sxw files again.
To be honest, I lost a lot of documents because I could not find a working copy of the word processor that I created them with - i.e. before or early Windows software.