Oh, that's what "ninched" means!
Way back when I mentioned "Temporal Ninching", using "ninched" to refer to a mixed state checkbox. I just learned, thanks to Murray Sargent's blog, that NINCH is an acronym for "no input no change"
I had the pleasure of working with Murray Sargent for a while when I was on the InfoPath, sorry, Microsoft Office® InfoPath™ team. At least at the time, InfoPath, Word and RichEdit were one big happy document-authoring family in the org chart. I confess that I don't remember the details, but we spent several hours discussing the finer points of text editing services.