Select the variable definition, either message type or element. Then select a variable from the list.

Open the Fault Variable Definition dialog from the Properties view of a catch container.

After receiving an inbound fault message, the fault handler assigns the inbound fault message to the variable before proceeding to perform the activity enclosed by the catch. Since the variable is declared within a fault handler, it is not accessible outside of the fault handler much like a local variable is not accessible outside of its declaring scope.