Donald Arseneau writes:
 > Huh?  \relax doesn't generate a mathord (you are jumping to {} I think)
 >
 > > as this messes up spacing.
 >
 > It does mess up spacing in TEXT mode, by interfering with ligatures
 > and kerning.
 >
 > (as you well know.)

did know :-)

i can only claim lack of sleep ...

frank