What must be true about the tables joined in maintenance view B in the ABAP dictionary?

In a maintenance view in the ABAP Dictionary, one of the fundamental requirements is that the primary table, which is typically referred to as the "main" or "primary" table, must have foreign key relationships defined. This ensures data integrity and proper linkage between the tables involved in the view. Specifically, the primary table must connect to foreign keys from the dependent or secondary tables.

This relationship is crucial because it allows for the systematic maintenance of records across the tables, ensuring that data modifications or entries in the primary table accurately correspond to related records in the secondary tables. Such constraints facilitate the enforcement of referential integrity, which is a primary purpose of defining foreign keys in databases.

In summary, the requirement for the primary table to have foreign key relationships underpins the primary role of a maintenance view, which is to allow users to maintain data while ensuring coherency and integrity across associated tables. This understanding reinforces the importance of foreign key relationships in the structure and function of maintenance views within the ABAP Dictionary.