What is necessary when creating a new structure in ABAP?

When creating a new structure in ABAP, defining the key fields is essential because key fields uniquely identify each record within the structure, ensuring that data can be accessed and managed accurately. These key fields establish the primary identifiers that differentiate one entry from another, which is fundamental for maintaining integrity within databases and ensuring that operations involving this data—such as querying, updating, or deleting records—can be performed reliably.

While existing structures might serve as a reference or basis for creating new structures, and assigning structures to programs is part of the broader development process, these actions do not substitute the necessity of having clearly defined key fields. Likewise, not every structure is necessarily stored in a database; some may exist purely for programmatic purposes within memory, emphasizing that the core component of creating a structure—its key fields—remains critical for proper data management and retrieval.