Which aspect is essential for the data requirements of a system?

A glossary is essential for the data requirements of a system because it provides clear definitions of terms and concepts used within the system. This clarity is crucial for ensuring that all stakeholders, including business analysts, developers, and users, have a common understanding of the terminology. It acts as a reference point that helps eliminate ambiguity in communication and documentation, which is vital when discussing data elements, their meanings, and their uses within the system being developed.

In contrast, while flow charts and control flow diagrams are useful for visualizing processes and workflows, they do not directly address the definitions of the data being used. Reporting requirements detail how data should be presented, which is important for data output but does not define the data itself. Therefore, the glossary stands out as the most foundational aspect for understanding and managing data requirements in a system effectively.