Metadata is an important element for achieving interoperability between Learning Objects systems; it facilitates the process of describing, searching, selecting and recovering of Learning Objects. The IEEE LOMv1.0 is a metadata standard for describing Learning Objects. Recently found evidence shows that the standard does not fulfill all requirements of its users, therefore they have extended it. In order to know the impact that extensions have into the interoperability, we made an international study where the use of the LOMv1.0 standard in forty-four works was analyzed. As a result we found fifteen types of extensions implemented to the standard. 
An international analysis of the extensions to the IEEE LOMv1.0 metadata standard