I'm not a Libretto user myself, but I've found a web page of handy
Libretto information that might be worth mentioning:

http://www.cerfnet.com/~adorable/libretto.html

-- 
Scott Telford,                        "It's a small miracle that computers are
Edinburgh Parallel Computing Centre    reliable at all: they function only as
University of Edinburgh, EH9 3JZ, UK.  the result of endless trial and error,
<s.telford@ed.ac.uk> +44 131 650 5978  folklore, and superstition." - J Kaplan