Case mappings are available only for message-targeted maps. Add
a case mapping in the following way:
From the Source view, select either one of the source or target
fields to which you want to add a case mapping.
Right-click the selected field and click Create
Case Mapping. The Compose Expression editor
opens.
Enter the case conditions for mapping into the Condition field. The default behavior at this point is for the source to be mapped directly
onto the target.
After you have entered the new conditions, click OK to
return to the Mapping view.
In the Compose Expression editor, you can add mapping expressions
that refer to sources and targets that have not been included as mapping inputs.