The connection rules describe how Systems are interconnected via Flows and how Interfaces are associated to their System.
The other sections describe Helper Symbols and Annotations, which increase readability and add meta information to the diagram, but do not alter the meaning of the diagram itself.
- Systems can have any numbers of Interfaces.
- Interfaces are connected to Systems by short straight lines.
- Flows to or from Systems are connected to the Systems Interfaces - never to the System itself.
- Interfaces can carry any number of outgoing or incoming Flows.
- Flows and Interfaces are of a specific type. A Flow can only connect to Interfaces of its own type - never to an Interface of a different type.
- Collectors bundle or fan out Flows. Consequently all Flows through a Collector must be of the same type.
- Notes are connected to any other symbol – including other Notes – via Associations.
- External Systems and Storages do not show their Interfaces, Flows connect to them directly.
Valid System Descriptions and Annotations
- Any diagram with at least one System connected to another System or External System following the connection rules is a valid Aspect of a System Description.
- A valid System Description is a collection of one or more valid Aspects.
- Any unconnected symbol, graphical objects or invalid connection of DA diagramming language symbols found in a collection of diagrams is called an Annotation and does not alter the meaning of the System Description.