The complexity of the verification and the validation of embedded systems is increasing. This paper explores the first requirements engineering processes in the solution domain, which are analysis and specification. In this work we present an architecture of a requirement specification system. We show how the requirements are analysed and structured to generate a dependency graph. This latter will serve to analyse requirements and to model specifications on goal model. In this paper we will focus on the analysis, and structuring processes. We will explain the requirement classification criteria.