ok I added the files this is better.
Yes, I could read the french article now. I am not quite convinced with the explanation of the back-tick though: "Un schéma peut contenir des variables en utilisant le backquote ou accent grave. Ainsi, `key représente nâimporte quelle variable, mais pas une expression." "`key" is a *meta-variable*, not necessarily a variable in the matched tree. Depending on the context it can also be a selector, e.g. "foo `key" matches all unary selectors sent to a variable called 'foo'. Ok, my french might not be that good :-) Also check page 42--43 of my PhD (http://scg.unibe.ch/archive/phd/renggli-phd.pdf): 4.1.1 Tree Pattern Matching. It is a bit dense and doesn't explain everything, but the basic matching is described and was successfully tested on students. Lukas -- Lukas Renggli www.lukas-renggli.ch