Returns the return value from the list that corresponds to the display value represented by displayValue.
Each entry within a list contains a display value (the value displayed to the user) and a
return value (the value returned to the server when a selection is made - this becomes the field value).
displayValue.Each entry within a list contains a display value (the value displayed to the user) and a return value (the value returned to the server when a selection is made - this becomes the field value).