CWA presents an Application Programmer Interface (API) for querying learning object repositories. The core is an abstract API; bindings to web services, Java and PHP have also been developed. Since one major design objective is to keep the specification simple and easy to implement, the interface is labelled Simple Query Interface (SQI). In the context of this CWA, learning object repositories are defined as collections of educational material, courses, and learning objects with associated descriptions (referred to as "metadata"). Examples of repositories for learning are educational brokers, knowledge pools, streaming video servers, etc. The decision for this work item was taken by the Learning Technologies Workshop at the 14th meeting on March 24/25, 2003. Work on the CWA actually started at the 17th meeting in April 2003. The document has been developed through the collaboration of a number of contributing partners, representing a wide mix of interests, from universities to commercial companies. The names of the individuals and their affiliations that have expressed support for this CWA is available at the CEN/ISSS Secretariat. A list of contributors is at the end of this Foreword