Landscape design software is used by landscape architects, landscape designers and garden designers to create planting, softworks, groundworks and hardworks (see definitions below) plans before constructing a landscape. There are two levels of software available, amateur and professional. The former is usually aimed at simple visualisation of a garden design whilst the latter provides tools that allow stylistic representations of a design to be accurately labelled and dimensioned for contractors to interpret and land authorities or local government to sight and approve or otherwise. Since the advent of the personal computer, several software packages have come into existence the main professional software being CS Design Software's CS Artisan, Idea Spectrum's Realtime Landscaping Architect, LANDWorksCAD, Keysoft Solutions' KeySCAPE LandCADD, Landmark, PRO Landscape, Structure Studio's VizTerra, VisionScape's VirtualProperty Architect, Visual Impact's Earthscapes, and Asuni's Lands Design. Professional landscape design software requires detailed information to be output for contract documentation, which will usually constitute drawings, specifications and reports (schedules/bills of quantity). The more sophisticated landscape design software solutions automate the process of generating reports (schedules/bills of quantity) from intelligent data in the drawing; such intelligence is usually contained within labels (annotations) which include, in the case of planting, automatic calculation routines to determine the number of individual plants based on plant spacings (centres) per area or length. When labelled areas or lengths are modified (stretched or shrunk), associated labels are recalculated at the same time as reports (schedules/bills of quantity) contained in or associated with the same drawing.