Final answer:
A high-level DFD that serves as the entry point into the system and includes the system and its interactions with external entities is referred to as a context diagram.
Step-by-step explanation:
A DFD created at the highest-level or summary level is referred to as a context diagram. This type of diagram serves as the entry point into the system. It includes the system as a whole and its external entities, such as customers, users, or other systems. The context diagram represents the entire system in its environment, showing the interactions that the system has with external entities. It is a high-level view that does not include details of the system's internal workings or processes. This diagram is essential for understanding the scope of the system and for setting the boundaries for more detailed DFDs, which can be developed at lower levels to represent the flow of data through various processes within the system.