Specification The quality of a design, product or service is a reflection of the quality of the design specification. also called the elementary product specification (EPS). The design specification is the DNA of a design. This is the core of the design process. This is the 'what' is the product specification in the design process. The 'how' to realize this is left to the knowledge and expertise of the designer. Usually the different phases are carried out by different people in the design process.