1The first number is the major version, corresponding to an “edition” of a conventional book. Versions differing by major numbers have been altered substantially. Chapter numbers and page references are not guaranteed to match between different versions. The second number is the minor version. Versions differing by a minor version may have serious errors/typos corrected and/or substantial text modifications. Versions differing by only the last number may have minor typos corrected, added references etc. When reporting errors, please mention the version number you are referring to.