It appears the only information on acceptable equation formats is in "Quick_Start_Guide_DOCX_Intake.docx", as an off-hand reference to "Unsupported OLE Objects", which states:
"(Supported OLE Objects include Visio.Drawing.11, Equation.DSMT4, ACD.ChemSketch.20, ChemDraw.Document.6.0, Equation.3)"
The one used with most versions of MS Word is "Equation.3". "Equation.3" had not been maintained for a number of years. Specifically, "Equation.3" was removed from all versions of MS Word in the January 2018 Word update, which is two years ago! (If they hadn't nailed him to the perch he'd be pushing up the daisies!) Microsoft suggests using something called "MathType" provided by WIRIS, but that is not on the 2-year old USPTO list.
Given that equations are a major reason to submit an application by .docx in the first place, it would be really helpful if direct and current information on acceptable equation formats were readily available.
Would it be possible to provide a temporary list in the meantime?