The sixth step commences once the optimum solution for PI

At every point, process models that are inefficient and that do not point to Pi are removed while analysis subsequent steps. At step four, a structural and logical approach in the synthesis of the problems and PI sub-problems and the constraints placed in the process are identified and redundant alternatives are delinked from the system. Then at step five, operational constraints are identified and feasible solutions relevant to PI are addressed at once. In the process, feasible variables are determined in the process and incorporated to achieve process efficiency.

The sixth step commences once the optimum solution for PI is reached, further steps in refining the solutions commence. That includes setting standards or benchmarks for PI operations against which they are evaluated to achieve operational efficiency as the seventh step.