Open Contacts has a formalised version number structure based around the NumVersion struct, which specifies a one- or two-digit major version, a one-digit minor version, a one-digit release version, and and multi-digit build number.
A major version is assiciated with more than 10 significant improved features, a minor version indicate one or more features added, and a minor version is with one or more bug fixes. The build number is the counter of compiler build on the program.
