**6.1 System evaluation**

A solid framework should be established that collects all necessary metrics for the purpose of system evaluation as a prerequisite to the study of system evolution. According to the ISO 14598 (1999) "Information Technology – Software Product Evaluation," there are four phases that the evaluation process should follow: (1) requirements, (2) specification, (3) design and (4) execution. We can classify and rearrange system metrics to cover these areas in the right order and then the underlying meta-structure will collect and generate system evaluations for any instant of time, as described in figure 1. System evaluation should have the flexibility to include new measures as it passes through evolutionary phases.
