The presence of an bio-chemical entity (substance) at a location or environment, such as an ingredient in a mixture, molecular part of a complex, a located entity at a cellular structure, or content of a container, such as a vesicle.
\nhttp://terminology.hl7.org/CodeSystem/v3-RoleClass
where concept is-a CONT, concept is-a INGR, concept is-a LOCE and concept is-a PART