Microsoft Word save "without maintain compatibility"?

Happy New Year to all, and a New Year question:

It seems that older versions of Microsoft Word let you save a file in DOCX format without maintaining compatibility with earlier versions of Word, by using this string in the “save as” statement:

without maintain compatibility

When I try to use this with the current version of Word, the script fails. Other people have reported the same problem in a few posts on other sites. I can’t find anything in Word’s dictionary that seems relevant, but I’m probably looking in the wrong place.

If anyone has an answer to this question, I’ll be grateful