Reading through the Language Reference I found no information about functions. I believe it would be helpful to have a clear link labeled: Functions Under the Structure Header pointing to the FunctionDeclartion page The follow page does not appear to be link to the Change page (or at least I can't find one)http://www.arduino.cc/en/Reference/FunctionDeclaration
I believe others may find it useful to know that one can create user define functions. The basic literature doesn't talk about or show any examples. I have not gone through all the tutorial example perhaps it is address in that location.