This application guide for cross-acceptance is a Technical Report about the basic standard. It is applicable to the same systems and addresses the same audience as the standard itself. It provides additional information on the application of EN 50129 to cross-acceptance. Therefore it deals with the acceptance by a safety authority of a previously accepted system or product in a different environment and/or context, often referred to as cross-acceptance. It is mainly dedicated to safety assessors, safety authorities, validators, and safety managers. In drafting this guide, it is assumed that the reader is familiar with the basic structure of the standard.