* Bruno Le Floch <[log in to unmask]> [2012-02-02 10:57:16 -0500]: Hi Bruno/all, I'm having some problem with expansion. The following is a contrived example of what's going wrong. I must be missing something obvious. \expandafter \xdef\csname #1\endcsname ##1{% \regex_match:nnTF{o}{o}{{0}{0}}{{1}{1}} } This defines some macro with the following definition: macro:#1->\regex_match:nnTF {o}{o}{{0}{0}}{{1}{1}} I'd have thought the body of an xdef would be fully expanded (unless you put an explicit \noexpand in front of an expression). Why doesn't the \regex_match expand? If there's any documentation I should read in order to understand this, please let me know where to find it. Lots of thanks in advance. Regards, Marc