A guide to relations in ENVO

Usage of 'composed primarily of' relation

In ENVO, we use RO:'composed primarily of' to describe the main constituent of a material entity. This is often a relation between an ENVO:'environmental material' and some BFO:'material entity' (including another kind of environmental material). For example, the ENVO:pedosphere would be RO:'composed primarily of' some ENVO:soil. ENVO:'environmental material' is a BFO:'fiat object part' - this means that we're dealing with portions of material (soil, water, etc) with no volume or boundary necessarily delineated by physical discontinuities.

We also use the RO:'composed primarily of' relation between material entities and chemical entities from CHEBI. For example, a portion of ENVO:'liquid water' would be RO:'composed primarily of' some CHEBI:'water'. This usage does not suggest that the material is primarily composed of a single water molecule, but this is being clarified through discussion on this issue, this should be parsed as: "material composed primarily of things of the same class as some molecule". More formal description will be available in the annotation properties of RO:'composed primarily of' (see this issue)