Testable specifications and implementing libraries do not always advance in parallel: a bug fix might result in a new release of a library without any change in the specification, for example, or the specification might be clarified or corrected without requiring any accompanying change in the implementation.
Specification documents therefore always include a prominent reference to the version of the implementing library they were tested against. The specifications themselves are identified by a three-part version number meeting the syntactic requirements of the semantic versioning specification in the form MAJOR.MINOR.PATCH. When referring to documentation, the following logic dictates when each part is incremented:
MAJOR version when the documentation applies to a new implementation of the library.MINOR version when the documentation expands coverage of an existing implementation of the library.PATCH version when an error in the documentation is corrected.