New unicode characters in C++0x

I'm buiding an API that allows me to fetch strings in various encodings, including utf8, utf16, utf32 and wchar_t (that may be utf32 or utf16 according to OS).

1. New C++ standard had introduced new types char16_t and char32_t that do not have this sizeof ambiguity and should be used in future, so I would like to support them as well, but the question is, would they interfere with normal uint16_t, uint32_t, wchar_t types not allowing overload because they may refer to same type?

   class some_class {
   public:
       void set(std::string); // utf8 string
       void set(std::wstring); // wchar string utf16 or utf32 according
                                // to sizeof(wchar_t)
       void set(std::basic_string<uint16_t>)
                            // wchar independent utf16 string
       void set(std::basic_string<uint32_t>);
                            // wchar independent utf32 string
   
   #ifdef HAVE_NEW_UNICODE_CHARRECTERS
       void set(std::basic_string<char16_t>)
                            // new standard utf16 string
       void set(std::basic_string<char32_t>);
                            // new standard utf32 string
   #endif
   };
   

   So I can just write:

   foo.set(U"Some utf32 String");
   foo.set(u"Some utf16 string");
   

2. What are the typedef of std::basic_string<char16_t> and std::basic_string<char32_t> as there is today:

   typedef basic_string<wchar_t> wstring.
   

   I can't find any reference.

   Edit: according to headers of gcc-4.4, that introduced these new types:

   typedef basic_string<char16_t> u16string;
   typedef basic_string<char32_t> u32string;
   

   I just want to make sure that this is actual standard requirement and not gcc-ism.