This graphic shows a mapping design that is invalid because the output of one operator violates the input requirement of the next downstream operator. At the top of this image are the following operators, ordered from left to right: TAB1, MM, JOIN, and TAB2. Below these operators is the operator CUSTOMERS.Data originates in TAB1 and flows to MM, representing the Match Merge operator. This is depicted by an arrow from TAB1 to MM. An arrow connects MM to JOIN, which in turn is connected to TAB2. An arrow connects CUSTOMERS to JOIN.