27 Input/output library [input.output]

27.2 Iostreams requirements [iostreams.requirements]

27.2.1 Imbue limitations [iostream.limits.imbue]

No function described in Clause [input.output] except for ios_base::imbue and basic_filebuf::pubimbue causes any instance of basic_ios::imbue or basic_streambuf::imbue to be called. If any user function called from a function declared in Clause [input.output] or as an overriding virtual function of any class declared in Clause [input.output] calls imbue, the behavior is undefined.