This paper seeks to extend the Work System Method WSM of Steven Alter by means of a modelling notation and mechanism called ABC. It does so because it is often necessary to know (or at least to conjecture) how things, processes and events interrelate. Our contention, which we support by literature primarily derived from cybernetics, is that we must discern conceptual models, so as to understand and, potentially, to improve by design, active models – specifically, the information systems which support work systems. We do this in order to regulate work systems, whether actively by explicit control or implicitly by aiding learning, understanding and self-control by modellers and participants. This paper is not a definitive statement concerning ABC. Instead, it sufficiently introduces the modelling approach to enable the reader to understand some examples of the approach as applied to work systems. It can also serve in a tutorial approach to the ABC modelling of work systems.