On my first go-around, I got:
I missed ADDRESS, BASE, BASEFONT, BDO, CAPTION, CITE, COL, COLGROUP, DEL, DFN, DIR, FIELDSET, INS, ISINDEX, KBD, LEGEND, MENU, OPTGROUP, PARAM, Q, SAMP, STRIKE, TFOOT, TH, THEAD, TT, and VAR. I never use those.
Or instead of being truthful, one could just change the score to something ridiculous 🙂
If there were that many elements, that would be insane! Even with all the propriety elements in frameworks like ASP.NET and Java Server Pages….egads!