Dear Junichi-san, Sorry to say, but I disagree. Surely compatibility issues should be covered in the Debian Policy manual. Esp. looking at Ubuntu compatibility is (or will become) highly important. If Debian doesn't care about the soversion set by other distros or by upstream, and every package maintainer is free to set his own, then _this_ should be documented. But not saying anything is surely the worst case. Regards Harri