External Entities are not permitted to communicate directly with data storage systems". This is one of the data flow diagram design guidelines. What does this standard entail

A taxi company would like to provide an online service for customers to book a trip and for taxi drivers to check their upcoming trips. A database needs to be created to store customer data (name, address, email, telephone number) and trip information (pick up and drop off address and pick up time and date). Furthermore, your database should contain driver information (name and license plate). Each trip must be assigned to exactly one driver (and trips for a driver must not overlap). Customers who are not registered yet need to register (providing their address, phone number, email address, and credit card information). A registered customer should be able to book a trip, i.e. provide the pick-up address and time as well as the drop-off address via a graphical user interface. Customers should also be able to view their trips and cancel them if needed. All these operations are only possible after a customer signs in (which means they must be registered). Each new trip must be confirmed…

Do you have any preconceived notions about what "data abstraction" entails? How may one use the many techniques at their disposal to partition a dataset into its constituent parts?

What does the word "data abstraction" mean to you? How may a dataset be subdivided?