The previous requirements modelling artifact for which system analyst might be responsible is user interface prototypes. The prototype itself can theoretically be mapped to UML Composite Structure diagram. However, when focusing on separate screen prototypes, people sometimes loose the screens which can be used by each actor, and the possibilities to navigate from each screen to the other screens. For capturing this information, we can create GUI navigation map, which is shown in Figure 7. In Figure 7, we use state diagram, where each state represents a screen, in which user is at the moment, and transition triggers represent GUI events, such as mouse double-click or clicking on some button, Using this requirement model, system developers create an effective software on inventory control and management system. The user interface diagram model is shown in Figure 8.