For your information, using the code I mentionned for \Uppercase, I have now two more things. - (Expandable) version of \tl_reverse:n that preserves spaces, and goes into brace groups, namely after two steps, \UL_reverse:n{\a{ b \) cd\(e}f} -> f{e\(dc \) b }\a - Expandable full-expansion code (which takes care of course of \unexpanded and \noexpand, and \protected commands). \fullyexpand:n{<some tl>} is then equivalent to \edef\tmpa{<some tl>} \tmpa I'm not too sure where I should go next. > I know of Uwe Lück's fifinddo.sty code, as part of the nicetext bundle: > <http://ctan.unsw.edu.au/macros/latex/contrib/nicetext/> Interesting. I will take a look. -- Regards, Bruno