ITG uses modelling techniques to express the impact of change requirements on the organisation's hierarchy, behaviour and supporting application structure. Capturing these models enables prototyping and allows the non technical and the technical to maintain a common definition of requirements. Agreed usage metrics are applied to these models to determine current and forecast capacity requirements. The target system architecture is established using configuration modelling providing an opportunity to re-test feasibility criteria prior to further significant investment. Agreed models are placed under change management.