The 4D/RCS Reference Model Architecture is a reference model for military unmanned vehicles on how their software components should be identified and organized. The 4D/RCS has been developed by the Intelligent Systems Division (ISD) of the National Institute of Standards and Technology (NIST) since the 1980s. This reference model is based on the general Real-time Control System (RCS) Reference Model Architecture, and has been applied to many kinds of robot control, including autonomous vehicle control.