The customer requirements are based on the expected use of the standard. The first consideration of any material standard is to make a supplier-independent specification of the material. Material from a certain grade must behave in a similar way regardless of the supplier. When the materials are heat-treated or subjected to various service conditions such as heat, cold or corrosive environments, the properties are affected. These effects depend on the chemical composition of the material. If the manufacturers are allowed to decide the composition of the material freely, unexpected differences in behavior between grades may occur. The addition or removal of a particular constituent would perhaps result in a different annealing temperature rending an unsatisfactory result or a component made from the material would start to behave differently in service. Either the material standard can specify the chemical composition or it has to be checked that the end result is the correct one by checking the microstructure. The first option is preferred since it gives the designer the possibility to predict other effects than just the material’s reaction to heat treatment. Checking the microstructure can be done either directly by a microscope or by checking a property related to the structure. The permitted ranges in the specification of the chemical composition must be carefully chosen to avoid sudden changes in material behavior. The TC who designs the standards must therefore have knowledge on the expected use.