Note: This plugin is no longer supported (since 2025).
Opaque (http://docs.moodle.org/en/Development:Opaque) is the Open protocol for
accessing question engines. It can be used to add questions to a Moodle quiz from third party assessment systems that support the protocol, like OpenMark or ounit (
http://code.google.com/p/ounit/) and possibly other question systems we don't know about.