National ITS Architecture Glossary

Every data flow included in the logical architecture of the National ITS Architecture is defined in a data dictionary entry. Each data dictionary entry contains a textual description of the data flow and identifies any lower level data elements that make up the data flow.

Representations of data flowing between processes or between a process and a terminator in the logical architecture of the National ITS Architecture. A data flow is shown as an arrow on a data flow diagram and is defined in a data dictionary entry in the logical architecture. Data flows are aggregated together to form high-level architecture flows in the physical architecture of the National ITS Architecture.

The diagrams in the logical architecture of the National ITS Architecture that show the functions that are required for ITS and the information that moves between these functions. Only four different symbols are used on the diagrams. Circles represent the processes or functions that do the work. Arrows represent the data flows that show how data moves through the system. Parallel lines represent data stores that represent "data at rest" in the system. Finally, rectangles represent the terminators that define the architecture boundary. A hierarchy of these diagrams depict the ITS functionality and data flow requirements in successively greater detail until "primitive" processes are defined.

A data store represents a reservoir in which data can be held for an indefinite period. Data stores are shown on the data flow diagrams where data repositories are required to support data aggregation or archival services.