In the meantime, you can only detect ambiguity by generating some mimicry and then parsing it. For that reason, try to avoid ambiguous grammars at all costs. Keeping them in Greibach Normal Form makes it somewhat easier to determine if this will happen. I hope you will take this occasion to generate some truly awesome grammars that spew out funny or at least inscrutable prose. If you come up with something interesting, please send it to me.
Many people like to include comments in sections of text.
I haven't included any special command, though, because it is possible to include comments in a trivial way. Simply define a variable that is never used elsewhere in the language. I realize this is a cheap solution, but it has the advantage of not turning another character into a special form. It is a cheap version of one derived by Steven Wolfram based on some of his work with Cellular Automata. I can't seem to find the reference right now.