Software Product Line Engineering is a collection of techniques that analyze the commonalities and variabilities of the products within a product family and produce products using such information. In Software Product Line Engineering, construction of the correct core assets is very important. To accomplish this, the commonalities and variabilities must first be definitively identified, both to provide traceability between the core assets, and to guarantee the reliability of the products. This paper suggests software product line development and test processes based on CVL for the differentiation of commonalities and variabilities. The proposed approach enables correct building of the core assets through procedures to keep traceability and guarantee the reliability of the products.