During this talk I will introduce the notion of a k-AOU space, which we may think of as a matricial Archimedean order unit space. I will then describe the relationship between the category of k-AOU spaces and k-positive maps, and the category of operator systems and completely positive maps. After demonstrating the existence of injective envelopes and C*-envelopes in the category of k-AOU spaces, I will describe a connection with quantum correlations. Combined with previous work, this yields a reformulation of Tsirelson's conjecture.