Reutilización de Requisitos de usuario: El modelo Mecano

The requirements of an Information System come of very diverse formats. Their storage in a repository and the relationships between them and with another reusable elements could condition the success or failure of a reuse program. It is necessary to introduce a minimum degree of normalization in the requirements, so that they can be really reusable. This is achieved initially by means of patterns. On the other hand, we must define consistent groups of requirements, related to reusable elements of other abstraction levels, in order to obtain an external interface for the reuse of complex elements. Lastly, we propose a guide to find common rules to different elements and obtain generic requirements, adaptive by means of parameterization to multiple situations (what imply parameterization of design and implementation elements). In this article we advance solutions to these problems, based on the experience with repositories.