ir desk. (Butler-Cox Plc, 1989, Informa- tion Technology and Building Design, London, 1.01). Therefore everyone will need at least two cable based services to their work Once the designer has the floor-plan available, the layout of IT space, data and voice, in addition to the power supply. components is planned. Various conventions exist to determine In order to accommodate this requirement the designer of the where layer or overlay information is stored. For example on a CAD building has to take into account any number of furniture and drawing which has 256 layers available, layer number 155 may be organisational configurations. This means that there has to be the reserved for floor outlets. The user can then view only the items capability to connect a variety of cables to distribution points from needed. This means the architectural shell and furniture layout virtually anywhere in the building. This requirement has brought could be viewed in conjunction with the floor outlets although the about the use of structured cabling. drawing may contain much more information such as the electrical Structured cabling reduces the number of cables required to sup- cabling and the HVAC services. port an organisation but increases the number of possible intercon- A Computer Aided Cable Design system will allow the designer nections within the network. In order to ensure that all to define a variety of symbols to represent a number of types of configurations are accounted for in both a structured and non- equipment. These can range from floor boxes to terminals, from structured environment an accurate design and documentation patch panels to computers and from multiplexers to MAU's. These method is required. This is best achieved using Computer Aided are, in most cases, not just graphical representations but can also Design (CAD) systems that produce drawings and related informa- contain considerable non-graphic data relating to the details of the tion electronically and much more accurately than manual methods equipment, suc