A few notes about the use and format of identifiers in ChEMBL: Each of the major entity types within ChEMBL (documents, assays, compounds and targets) are assigned unique ChEMBL identifiers, which take the form of a ‘CHEMBL’ prefix followed immediately by an integer ( e.g ., CHEMBL25 is the compound aspirin, CHEMBL210 is the human beta-2 adrenergic receptor "target"). There is no distinction between the format of the identifier for different types of entities, but a given ChEMBL identifier will only ever be assigned to a single entity ( i.e. , CHEMBL25 will only ever be used for the compound aspirin and never for an assay, document or target). A lookup table is provided in the database, to resolve which identifiers correspond to which entity types. ChEMBL identifiers are stable with respect to the entities they represent. For compounds (with known/defined structures), ChEMBL identifiers represent distinct compound structures, as defined by the standard InChI, e.g.,...