[boost] user defined facets in date_time library

While trying to make date_time tests compilable on tru64cxx65, I have come accross an issue with user defined facets (namely date_names_put and all_date_names_put) that leaves me scratching my head. Is a user defined facet required to be default constructible? Or does it need a constructor of the form "foo(size_t refs = 0) : locale::facet(refs) {}"? [lib.facets.examples] doesn't say so but most examples I could find either have a default constructor or a constructor taking a reference count. Markus