The holy grail of biomedical modelling is an integrated model of the entire human body. To this end, research groups around the world need to interchange experimental data, models and model results. A good interchange will have an efficient representation for storage and sharing and will have tools for modelling, data verification, authoring, data conversions and so on. A field is a spatially varying properly. In this paper we present the abstract field layer (AFL) and the field representation language (FRL). The AFL provides the field abstraction together with a set of common field operations. The FRL provides an efficient means for field representation and storage. We show how fields can be used to interchange information between modelling systems and between modelling and visualisation systems. We are currently developing a software system that composes multiple single cell solvers to create a tissue solver.