In this document we explain some basic concepts of the AIL (Architecture Implementation Language), as it has been defined in the AEE (Architecture Electronique Embarquée) French research project. Relations with the XML (eXtensible Mark-up Language) technology are highlighted. Finally, we compare some aspects of the four layer meta model of the AIL with the UML+extensions based meta model that is to be defined within the context of the EAST-EEA European research project. The purpose is to help those that have defined the AIL to understand the UML+extensions approach and to help the others to understand the AIL.