Hello
I updated the following Wiki pages for the possible use of <expression> in animations:
http://wiki.flightgear.org/Howto:Animate_models :
--> I added the possible use of expression in "Special Code Parts" paragraph and references to "expression" for each animation supported
http://wiki.flightgear.org/Expressions :
--> alphabetically sorted the list of possible elements and found and removed two redundancies from the list.
Remark: I got the information from the http://wiki.flightgear.org/FlightGear_Newsletter_February_2012 and as I couldn't find the related information where I expected it to be, I decided to update and hopefully improve the Wiki.
As I havn't verified what is said about the use of expression yet, I kindly ask someone who knows more about this to check my changes and correct it if I got something wrong.
Thanks
Mike-DE