Hi all, Based on the discussion on this subject, I am going to switch to the automatic scheme of ID genereation. As I understand, the need to specify a unique ID could introduce just enough inconvenience to make the system unattractive to use. I will put registration classes inside anonimous namespace, to avoid ODR violation when typeof os used from a CPP. When typeof is used in templates, or enywhere else inside a header (except classes also defined in anonimous namespaces), the system will not be ODR-complient. The compilers will probably not care (since there is no runtime code generated, but this will have to be tested. I will make the changes and post them sometime soon. Anybody has any problems with this approach? Arkadiy