Minor Versions
Within a major version of a framework, you can also designate the current minor version. Minor versions are also referred to as “compatible versions” because they retain compatibility with the applications linked to the framework. Minor versions don’t change the existing public interfaces of the framework. Instead, they add new interfaces or modify the implementation of the framework in ways that provide new behavior without changing the old behavior.
Within any major version of the framework, only one minor version at a time exists. Subsequent minor versions simply overwrite the previous one. This differs from the major version scheme, in which multiple major versions coexist in the framework bundle.
The following sections describe how you designate minor version information in your framework and how the system uses that information to ensure applications can run.
Minor Version Numbering Scheme
Frameworks employ two separate numbers to track minor version information. The current version number tracks individual builds of your framework and is mostly for internal use by your team. You can use this number to track a group of changes to your framework and you can increment it as often as seems appropriate. A typical example would be to increment this number each time you build and distribute your framework to your internal development and testing teams.
The compatibility version number of your framework is more important because it marks changes to your framework’s public interfaces. When you make certain kinds of changes to public interfaces, you should set the compatibility version to match the current version of your framework. Thus, the compatibility version typically lags behind the current version. Only when your framework’s public interfaces change do the two numbers match up.
Remember that not all changes to your framework’s public interfaces can be matched by incrementing the compatibility version. Some changes may require that you release a new major version of your framework. See Versioning Guidelines for a summary of the changes you can make for each version.