This report defines version 2.0 of the Open Checklist Interactive Language (OCIL). The intent of OCIL is to provide a standardized basis for expressing questionnaires and related information, such as answers to questions and final questionnaire results, so that the questionnaires can use a standardized, machinereadable approach to interacting with humans and using information stored during previous data collection efforts. OCIL documents are Extensible Markup Language (XML) based. This report defines and explains the requirements that IT products and OCIL documents asserting conformance with the OCIL 2.0 specification must meet.