NEMA NTCIP 1201:2011

The messaging between the Transportation Management Center and field devices is accomplished by using the NTCIP Application Layer services to convey requests to access or modify values stored in a given device; these values are referred to as objects. NTCIP 1201 v03 identifies and defines object definitions that may be supported by multiple device types (e.g., actuated signal controllers and dynamic message signs). In the NTCIP family of standards, objects for a given device type are grouped in a device-type-specific data dictionary standard.