Abstract
In the previous decade, more and more de facto standards of enterprise modeling languages (EML) evolved. The establishment of EMLs leads naturally to an increasing number of EML extensions in order to integrate requirements and needs from specific problems or domains in an EML. Thus, EML extensibility is proposed as a relevant topic within both the field of meta modeling and enterprise modeling. We therefore conducted an analysis of existing meta modeling languages and well known EML languages in order to derive the current state of the art in terms of EML extensibility. In addition to that, classification schemes for extension purposes and extension mechanisms are presented. Finally, topics for further research are proclaimed in order to facilitate more research on language extensibility.