Preface Proceedings of the MODELS 2013 OCL Workshop Co-located with the 16th Int. ACM/IEEE Conference on Model Driven Engineering Languages and Systems MODELS 2013 UML and its precursors exemplify the use of a graphical notation for modeling. Such visual representations enable direct intuitive capturing of reality, but some of their features are difficult to formalize and lack the level of precision required to create complete and unambiguous specifications. Limitations of the graphical notations encouraged the development of text-based modeling languages that either integrate with or replace graphical notations for modeling. Typical ex- amples of such languages are OCL, textual MOF, Epsilon, and Alloy. Textual modeling languages have their roots in formal language paradigms like logic, programming and databases. The goal of this workshop was to create a forum where researchers and practi- tioners interested in building models using OCL or other kinds of textual lan- guages could directly interact, report advances, share results, identify tools for language development, and discuss appropriate standards. The close interaction enabled researchers and practitioners to identify common interests and options for potential cooperation. Every accepted paper was reviewed by at least three members of the program committee. – Thomas Baar, University of Applied Sciences Berlin, Germany – Mira Balaban, Ben-Gurion University of the Negev, Israel – Tricia Balfe, Nomos Software, Ireland – Fabian Büttner, Ecole des Mines de Nantes, France – Achim D. Brucker, SAP Research, Germany – Yoonsik Cheon, University of Texas, USA – Dan Chiorean, Babes-Bolyai University, Romania – Robert Clariso, Universitat Oberta de Catalunya, Spain – Tony Clark, Middlesex University, UK – Manuel Clavel, Universidad Complutense de Madrid, Spain – Birgit Demuth, Technische Universitat Dresden, Germany – Marina Egea, Atos Research, Madrid, Spain – Pieter Van Gorp, Eindhoven University of Technology, The Netherlands – Heinrich Hussmann, LMU Munchen, Germany – Tihamer Levendovszky, Vanderbilt University, USA – Shahar Maoz, Tel Aviv University, Israel – Shane Sendall, Snowie Research SA, Switzerland – Michael Wahler, ABB Switzerland Ltd Corporate Research, Switzerland – Claas Wilke, Technische Universitat Dresden, Germany – Burkhart Wolff, University Paris-Sud, France – Steffen Zschaler, King’s College, London, UK Additionally these proceedings include an unreviewed paper describing the dis- cussions which took place during a follow-up meeting to the OCL workshop held in November 2013 where short term improvements for the OMG standardization process and long term developments of OCL were discussed. Jordi Cabot, Martin Gogolla, Istvan Rath, Ed Willink November 2013