The October 2009 memo (.pdf), widely seen as a landmark for its assertion that open source software qualifies as a “commercial item” under federal and Defense acquisition policy definition of the term (and so removing a previous barrier to is wider use), also stipulated that program managers before using open source software must “ensure that the plan for software support…is adequate for mission need.”
That requirement has been widely interpreted by some in military services to mean that any open source tool without a support contract is verboten, leading to instances where even basic tools such as a software compiler have been called into question for lack of a service vendor.