A critical document in the design process that is usually overlooked is the Product Design Specification or product design specification (PDS). The problem of converting the frequently non-technical, non-quantifiable customer requirements to a set of product characteristics expressed in engineering terms leads to the PDS. The starting point of any PDS is the brief that is put together by the marketing department and describes what the customer is requiring. In case the product is more generally commercially orientated, the data would usually have been obtained from ‘focus groups’ or other marketing techniques. Product brief provides a brief description of the products purpose and the reasoning for developing the product including any technical factors that call for a new product. Any special product testing that requires further study before the product is fit for sale. Any marketing issues that need to be investigated further to help build a better picture of the future sales of the product.