When I build the serialization library I get two copies of the diagnostic message. I asked this before but now I can't find the answer. It seems that it was suggested that this was symptom of some sort of mistake that could/should be corrected. In studying this I've come upon the following scenario. library ab contains a.cpp - with interface in a.hpp b.cpp - with interface in b.hpp User programs might contain a.hpp or b.hpp or both depending on what they want to call. So each of a.hpp and b.hpp should contain auto-link to generate the pragma corresponding to the library ab. However if, it the user includes both a.hpp and b.hpp - which he gets two diagnostic messages - since auto_link.hpp has no include guard. If this is a mistake, where is it and who is making it? Robert Ramey