User blog comment:Bubby3/Letter notation extension to R and higher letters/@comment-39541634-20191219105141

The P10=Q3 problem is easy to fix: Just set φ1(0)[0]=1 instead of 0. A bit ad-hoc, perhaps, but it gets the job done. There are also ways to make it look more natural, once we go beyond Veblen and start using OCF-based notations. ε0 often gets special treatment in these notation, anyway.