This fourth part comprises three appendices which summarize various aspects of the relationship between Ada 83 and Ada 95. Appendix X covers the incompatabilities of which there are few of real significance. Appendix Y gives the main changes betwen the Committee Draft, the Draft International Standard and the final International Standard; it shows that these changes are few and hence that the final language has had the benefit of considerable stability throughout the review periods. Appendix Z is a brief summary of the mapping between the original Requirements and the sections of this rationale where they are addressed; it concludes that Ada 95 meets the Requirements.