GABLE CAD SYSTEMS comprise a suite of integrated sub-systems, one of which is OMS. The use of OMS in the development of a building design enables three dimensional graphical modelling of objects associated with buildings. Thus furniture, fittings and fixtures may be located within any room in a building or outside a building or in relation to other groups of objects unrelated to a building. Once located, objects and building may be seen in 2D plan and elevation/section projection or 3D projection (perspectives, axonometrics, isometrics, etc.). In this way furniture, people, cars, trees,landscape objects may all be modelled and graphically represented in addition to the modelling capabilities enabled using GABLE BMS (Building Modelling System). These graphically represented 2D and 3D views of objects can then be passed into GABLE IDS for further embellishment, annotation or dimensioning to produce detailed working drawings.