Once a system delivers its primary value-related function, there is no reason why it should not also be designed to deliver other secondary value-related functions. Team X could produce the design and secondarily create reports to document the decision. The circulatory system could return carbon dioxide to the lungs, in addition to delivering oxygen. The operational amplifier could filter high-frequency noise, in addition to amplifying.

It is important to identify these secondary functions, because they are expected by customers and are a source of competitive advantage. Question 5d of Table 5.1 is “What are the other important secondary value-related external functions?” These other value-related external functions must also emerge from the internal processes. The procedure to address this question is just to repeatedly apply the reasoning for the primary value-related function to these ­secondary functions.

The centrifugal pump could have secondary value-related functions. Many water pumps have a “slinger” to sling water that leaks through the rotating seal away from entering the electric motor. The pump could also include a pressure sensor that indicates the outlet pressure of the water, a measure of the property associated with delivery of the primary value. Figure 5.20 shows the two secondary value-related functions. One appears along the principal value pathway, the other on its own pathway.

In summary:

• Systems deliver secondary external value-related functions, in addition to the primary value-related function for which the system exists.