This paper proposes that within the Land domain, there is not only a need to define an approach to open architectures, but also to mandate their use, in order to provide an agile framework for our fighting forces going forward. The paper sets out to explain such an approach; that taken by UK MOD and industry to produce the Generic Vehicle Architecture (GVA) defense standard. It will discuss how the GVA standard was formed, how it is currently being used and how it contributes to the wider MOD initiative for Open Systems Architecture for the Land domain. Finally the paper considers how the UK GVA relates to the US Victory standard and how interoperability may be achieved.