Case mappings are a set of rules that define the many possible conditions under which to apply the mapping. They are available for message-targeted mapping only.
Message mapping is usually unconditional, meaning that the assignment is always performed. There are times when the assignment should be performed only if a certain condition or set of conditions have been met. You can create a case mapping, then use the Compose Expression editor to define the rules that control this. You can specify an arbitrary number of conditions and corresponding assignments, including a default assignment that is used if all others are untrue. All these assignments map to the same target, and they can be manipulated or deleted as required.
For a simple drag-and-drop mapping, a conditional statement is generated in the format if s_field is not null and a check box is available to indicate whether the condition should be applied.