Definition: A discrete biological unit used when describing pathways. Rationale: Entity is the most abstract class for representing interacting elements in a pathway. It includes both occurents (interactions and pathways) and continuants (physical entities and genes). Loosely speaking, BioPAX Entity is an atomic scientific statement with an associated source, evidence and references. Synonyms: element, thing, object, bioentity, statement.
Source:http://www.biopax.org/release/biopax-level3.owl#Entity