Flow groups are used to group flows in a selection in order for them (as a group) to be viewed as a singel alternative.
The flow group Group2 seen in this example is used to let each variant have their own flow; Var1 with flow OP1Flow through operation OP1 and Var2 with flow OP2Flow through operation OP2, but still together be seen as one alternative in the flow selection.
Note: More details about the flow selection in the example is found under flow selection.