>> Perhaps you meant >> >> \csname\ifnum 3>2\fi\endcsname >> >> which indeeds does \csname\relax\endcsname, an error. > > We should be fine here in expl3, I think, as internally we have > something like > > \csname\ifnum\numexpr3\relax>\numexpr2\relax\fi\endcsname > > in this scenario, and that is fine. Precisely. If there were stray "implicit \relax", then they would appear in x-expansion as well. Bruno