What feature does an insert definition provide to users?

The correct answer highlights a crucial feature of an insert definition, which is to grant users control over which fields permit the creation of new reference records. This functionality is essential because it allows administrators to define the structure and integrity of the data within the application. By specifying which fields can be used to create new entries, the system ensures that only valid and relevant data is captured, thereby improving data quality and consistency.

This control is particularly beneficial in scenarios where specific conditions or validations must be met before new records can be added. By regulating the input points for new references, users can avoid potential errors or inconsistencies in the dataset, ensuring that the information is reliable and aligned with the organization's data management policies.

In contrast, the other options pertain to different aspects of user interface or data entry management that do not specifically relate to the central function of an insert definition, making them less suitable answers in this context. For instance, while customization of sheet colors or limiting the amount of data entered can enhance user experience, they do not address the fundamental role of an insert definition, which is to govern data entry at a more granular level.