Hi Stefan, > As I understand it, the anonymous namespace has internal linkage... Sort of, but not really. If you look at your object code, you will see that the symbols in the anonymous namespace have external linkage. (But the symbol will be mangled with a different random prefix or suffix, or perhaps some other unique-ifying technique.) I'm not up on the latest C++0x. Perhaps the anonymous namespaces have external linkage is changed. The "whys and wherefores" for external linkage with anonymous namespace -- I can't remember off the top of my head. GUIDELINE: header files should not contain anonymous namespaces. (At the moment, I cannot think of any exceptions to that guideline.) Sincerely, --Eljay