Substance represents a homogeneous material with definite composition that includes allergens, biological materials, chemicals, foods, drugs and materials.19 QDM distinguishes between medications from non-medication substances by separately listing medication datatypes. Substance may or may not have a code or be classified by a code system such RxNorm. Examples of a substance may include environmental agents (e.g., pollen, dust) and food (e.g., vitamins).
An assertion of a physical or conceptual entity, relationship, role, situation, condition, or phenomenon present or absent.