The Impact Acquire interface (API) uses the semantic versioning scheme based on Semantic Versioning since version 2.0.0:

The version format is X.Y.Z (MAJOR.MINOR.PATCH.BUILD), e.g. Impact Acquire 1.12.57.

Given that scheme:

incompatible API changes increment the MAJOR version
backwards compatible API additions/changes increment the MINOR version
Bug fixes not affecting the API increment the PATCH version
Builds trigger by the continuous integration system increment the PATCH version

For details please refer to http://semver.org/.

In addition to that the version of the Impact Acquire API can now be evaluated at compile time. This will allow users to write code that can be compiled with different versions of Impact Acquire in case an interface change was introduced.

For example, to test if the program will be compiled with Impact Acquire 2.0.0 or higher, the following can be done:

HDISP hDisp = getDisplayHandleFromSomewhere();
#if MVIMPACT_ACQUIRE_CHECK_VERSION(2, 0, 0)
  mvDispWindowDestroy( hDisp );
#else // replacement code for old version
  mvDestroyImageWindow( hDisp );
#endif