A custom field application defines which members or entities a custom field applies to. By default, custom fields apply to all members. However, custom field applications allow you to target specific members, roles, badges, or pricing plans, or exclude certain entities.
Custom field ID.
Custom field key.
Entities to which the custom field applies.
Entities from which the custom field is excluded.
Revision number, which increments by 1 each time the custom field is updated. To prevent conflicting changes, the existing revision must be used when updating a custom field.