In Experience Data Model (XDM), an enum field represents a field that is constrained to a pre-defined list of acceptable values.
When defining a new field in the Adobe Experience Platform user interface, you can set it as an enum field by selecting the Enum checkbox in the right rail.
Additional controls appear after selecting the checkbox, allowing you to specify the value constraints for the enum. Under the Value column, you must provide the exact value you want to constrain the field to. This value must comply to the Type you selected for the enum field. You can optionally provide a human-friendly Label for the constraint as well.
To add additional constraints to the enum, select Add row.
Continue to add the desired constraints and optional labels to the enum. When finished, select Apply to apply the changes to the schema.
The canvas updates to reflect the changes. When you explore this schema in the future, you can view and edit the constraints for the enum field within the right rail.
This guide covered how to define an enum field in the the UI. See the overview on defining fields in the UI to learn how to define other XDM field types in the Schema Editor.