Abstract
Pattern languages should capture design knowledge for one domain and be useful for solving genuine problems in that field. The "rule of three" demands that a pattern should have at least three known uses to be considered a pattern. However this is not a strong evaluation to verify if the pattern language fulfills its objectives. This paper proposes a process to evaluate a pattern language, which was used in the analysis of the Pattern Language for Metadata-based Frameworks. As a result, it enables the determination of each pattern confidence level and the assessment of the usefulness of the pattern language as a whole.