Which namespace does operator<< (stream) go to?

Question

If I have have some overloaded ostream operators, defined for library local objects, is its okay for them to go to std namespace? If I do not declare them in std namespace, then

Answer 1

According to Koenig Lookup (C++ Standard 3.4.2) operator<< will be searched in namespaces of arguments. No need to declare it in std namespace.