At the recent RuleML+RR+DecisionCAMP event in London several vendors presented their common work that demonstrated “The Effectiveness of DMN Portability“. This paper introduces DMN with a focus on the portability of its executable profile across computational platforms. The paper proposes a cross vendor collaboration challenge, “Vacation Days” from the Decision Management Community, to test the effectiveness of the standard for use in cross vendor situations. The different degrees of compliance and extensions as supported by the vendors is also discussed. See also DMN Interchange in Action