The Display tab of the Edit Unit Window controls how the unit is displayed, how it’s values and labels are formatted and displayed and any colors or icons associated with the Unit.
By filling in the comma separated list of values you enable the ability to use enumerated values with the Set Value command. When setting the value of the above example you would not have to remember that numerical index for the “cool” setting is 2. You could simply do a:
set value of “my unit name” to “cool”
and as long as the string you pass matches one of the comma separated values it will set it to the proper numerical value under the hood. If you set the value to a string that is not in the list an error will be logged and the value will default to -1. No applescript error will be returned however so your script will continue to run.