What is one way to ensure that an attribute is mandatory in a governed entity?

To ensure that an attribute is mandatory in a governed entity, selecting the required check box in the data model is the most effective method. This action directly modifies the data governance framework within SAP MDG, defining the attribute's status as mandatory at the data model level. By marking the attribute as required, the system is configured to enforce this rule during data entry and validations, ensuring that users cannot save or submit records without providing a value for this attribute.

The other options, while potentially useful in different contexts, do not fundamentally enforce the mandatory nature of the attribute. For instance, using a custom ABAP program might introduce complexity and require ongoing maintenance, while setting a default value does not compel users to enter data, as they might override the default without inputting their own value. Implementing user training sessions can improve compliance and understanding, but it does not provide any system-level enforcement of mandatory fields. Hence, adjusting the data model through the required check box is the most direct and reliable approach to achieve this goal.