Authors: Inga Hege, LMU Munich/Germany and Jörn Heid, University of Heidelberg/Germany
There are three systems that will be used as representatives for a system based on a linear/string of pearls approach: TUSK, CASUS (http://casus.eu) from Munich and CAMPUS (http://virtual-patients.com) from Heidelberg.
CAMPUS and CASUS can play cards on which a situation is displayed. After the card the student can continue to the next card - there's only one way to get to the one next card (in contrast to a branching approach).
Because of that each card can have interactive elements, like knowledge questions.
Usage of MVP VP Elements
The linear/string of pearls approach uses very little of the ActivityModel (no rules or timers normally), but there might be implementations that can use the timers.
The didactical concept uses knowledge questions instead of branching so that the XtensibleInfo element is necessary and the current QTI implementations look promising although the complete support of the whole QTI spec is very hard to achieve.
Even if one system can export most of the spec there won't be many systems that will be able to play as it's not part of the MVP VP spec.
Additionally, question types supported by the two systems are not available in QTI at the moment - for instance long-menu (CAMPUS, CASUS) or region of interest (CAMPUS) questions.
CAMPUS also uses the XtensibleInfo for storing the complete, proprietary export data (GZIPed and base64 encoded), so that the re-import is possible without any loss and additionally information could be extracted with special players or applications.