BAO 2.0 main classes with some relationships between them. Six main components (shaded classes) are used to formally describe bioassays by terms related to bioassay, biology, screened entity, assay method, format, and endpoint. The most important classes and their relations as shown including bioassay, measure group, biological macromolecule, screened entity, assay method (specifically assay design method and physical detection method), assay format, and endpoint. There exists complex interactions among these entities. OWL DL 2 (SROIQ(D)), the decidable subset of the first-order-predicate logic provides the interpretations, models, and logical consequences.