Hi, I have spent several hours looking at the docs and sources, but I cannot figure out how to allow multiple occurances of an option. Many unix tools allow you to specify the --verbose option multiple times, to mean increasing verbosity of output, and I want to replicate this behaviour. Does this require writing a new class derived from value_semantic, that combines the behaviour of bool_switch() and typed_value<std::vector<bool>> ? I'm not sure how to go about doing that. It is a very useful lib, but I do wish (often!) there was some real reference docs (aside from the doxygen stuff and comments in the sources themselves, which isn't enough :-( Unrelated, but in trying to figure this out from the docs, I noticed in the overview.html, in the Syntactic Information there is a call to a function value<string>()->implicit(). However typed_value<T> has no such member function. Maybe it is left over from a previous design iteration or something, as there is a member variable m_implicit but it is never initialized or accessed. Cheers, Ian McCulloch