ABSTRACT
Regardless if you are designing a train or a toothbrush, specifications can be used to provide explicit requirements. This often come in the form of physical dimensions (e.g. maximum size, location and size of interfacing parts), environmental factors (e.g. temperature and humidity to withstand), ergonomic factors (e.g. description of the target population), aesthetic or sensory factors (e.g. requirement to represent brand values), cost (e.g. material, manufacture, purchase), maintenance that will be needed, quality, and safety.
