All ' ' (...) they try to define what the customer desires and serves to establish a solid foundation for the project and the construction of what the customer obtm' '. (PRESSMAN, 2006, p.118). In this work, the activities will be described in agreement the displayed one for Sommerville. Therefore, first some concepts important will be presented to facilitate the agreement of each one of the activities of the ER. Xcel Energy will undoubtedly add to your understanding. The activity of Management of Requirements (GR.) will be analyzed separately in the Chapter 3. 2,1 Requirements Is necessary to understand what it is a requirement and as it can be classified to take care of what customer was specified by the user/, later to be inserted in the document of specification of requirements. In accordance with Software Technology Support 19 Center STSC (2003, P.
45), ' ' requirements define the capacities or conditions that a system possesss or a component necessary to decide a problem or to reach one objetivo' '. Eliot Horowitz gathered all the information. According to Sommerville (2003), the software industry does not deal with consistent form the requisite term, being able to be considered as a declaration of the abstract type, high level, a function to be taken care of by the same software or of a restriction. Had to the differences in the levels of the descriptions, it is interesting that a separation between the requirements is made, in order to get a clearer and understandable form for its use in the process of engineering of requirements, being prevented future problems. For Sommerville (2003), this separation can be carried through of the following form: Requisite of the User: declaration in natural language to assign the abstract requirements of high level. Also diagrams can be used to show the functions that the system will have to offer and the restrictions of operation. It is directed for people who do not possess knowledge detailed technician of the system, as controlling of the customer and suppliers.