Researcher Brian Tivnan summarizes Holland's work thusly:
Holland (1995) describes a CAS according to what he refers to as the “seven basics” - four properties and three mechanisms; when simultaneously occurring, this set of seven basics constitutes the necessary and sufficient conditions of all CAS. The four properties consist of (a) aggregation, (b) nonlinearity, (c) flows, and (d) diversity. The three mechanisms consist of (a) tagging, (b) internal models, and (c) building blocks. More than their distinction as properties or mechanisms, Holland emphasizes the importance of the interrelations between the seven basics.