Every side-by-side assembly must have a version. Each assembly version is associated with a version number having four parts separated by periods: major.minor.build.revision. If a change is made to an assembly making it incompatible with existing versions, the major or minor parts of the version number must be changed. A version number that changes only in the build or revision parts indicates that the assembly is backward compatible with prior versions.
The version must be specified in assemblyIdentity elements of manifests. Use the four-part version format: mmmmm.nnnnn.ooooo.ppppp. Each of the parts separated by periods can be 0-65535 inclusive.