Which feature must a domain be applied to for value validation to work?

The functionality of a domain in a GIS environment is linked specifically to fields within a table. A domain is a set of valid values that define the acceptable entries for a specific field in the database. When a domain is applied to a field, it enforces value validation, ensuring that only predefined values can be entered into that field. This helps maintain data integrity by preventing invalid data from being recorded.

In contrast, other choices, while they relate to GIS, do not serve as direct sites for applying value validation through domains. A title may refer to a layer or project but does not encompass data validation capabilities. A layer is a representation of geographic data but doesn't itself hold domain constraints; it's the fields within tables that do. Similarly, a table contains fields but is not where domains are applied directly. Thus, it's the field that is the specific feature where a domain must be applied for the validation of values to effectively occur.