The SPL standard is one of many applications of the HL7 RIM. It is a knowledge representation standard for drug products. Prior to SPL there was no data standard for medication knowledge (outside of proprietary products) able to express even the basic realities of medicines, ingredients and packaging in a computable way. All pharmaceutical manufacturers in the U.S. submit drug information to the FDA using SPL and the NLM publishes them online.  The SPL knowledge base presently contains over 3200 descriptions of currently marketed drugs. SPL, which includes data relevant for clinical decision support such as adverse effects, contraindication, interactions, and monitoring requirements, serves as preliminary evidence that it is indeed possible to integrate medical knowledge into a standard which was driven by practical health information systems. Within the SPL structure all the terminologies of the U.S. federated medication terminology system come together: the NDC product code, Unique Ingredient Identifier (UNII), SNOMED CT disease / finding concepts, the VA NDF-RT system’s ChemicalStructure classes (originating in the NLM MeSH system), physiologic effect and the mechanism of action terms (described in detail below). SPL also combines several smaller vocabularies from the NCI Thesaurus and the Unified Code for Units of Measure.