Metamodel for developing information system models of health information systems. It distinguishes three layers of information systems: domain layer, logical tool layer, and physical tool layer. It aims to support the systematic information management and especially the structural monitoring of information processing in health care institutions. 3LGM²-B consists of concepts describing basic elements of a HIS architecture. 3LGM²-M adds concepts for modeling message-based communication. 3LGM²-S provides additional concepts for modeling service-oriented architectures. @en