The sharing and exchange of assessment data between educational applications is a novel aim in learning technology. Question and Test Interoperability (QTI) is a learning standard for coding assessment data. It was created in order to promote interoperability between assessment tools. For tools to be interoperable, they need to have a high level of conformance to the QTI specification. The main aim of this paper is to methodologically evaluate the conformance of authoring tools to QTI. The evaluation showed that most of the tools have implemented only a small part of the learning standard.