APPLICATION DESIGN
For example, a Service Request form contains a Priority field, which uses the following choice list:
Urgent High Medium Low
You want the By Priority view to sort documents by the value in the Priority field, but you don't want them to appear in ordinary alphabetical order (High, Low, Medium, Urgent). You want users to see Urgent-priority documents at the top of the view, High-priority documents next, and so on.
You create a column that:
@If(Priority="Urgent";"1";Priority="High";"2";Priority="Medium";"3";"4")