STRUCTURE: Single Choice List heading
This type of heading requires a List of values to be defined. This list can be sorted manually or in alphabetical order. As its name indicates, the value taken by a resource (in the case of a resource heading) or by an event (in the case of a form heading) is unique in the list of values.
You can add a Default Value to it, chosen from the values in the list.
Finally, you can use the AutoFilter :