Components in the STEP standard:

There are five components in the STEP standard.

(i) The first component discusses the reason of the standard. It contains following:

a) an overview explaining the fundamentals of the whole standard,

b) EXPRESS is a formal language for specify the information structures that are needed to described the product model of STEP.

c) Framework for product modelling in which the fundamental methods of modelling are defined.

 (ii) The second component described standards for implementation of STEP. It has physical file implementations that define the rules according to which the data structures described in EXPRESS are mapped on a segmental data file.

 (iii) The third component indicates the framework for conformance testing. This segment described the rules according to which an implementation is tested for standard conformity.

(iv) This component involved standards for product modelling .The models include following:

a) A presentation model which described the type of presentation of information. For example how the product may be visualized on a CRT or paper. Features as colour, illumination, view angles, text font.

b) Materials model: is where the characteristics of material may be described. For example an elasticity matrix, material-specific coefficients such like a coefficient of expansion, heat transfer, thermal conductivity.

c) Tolerance model define dimensional tolerances, geometric tolerances.

d) Surface model describes the specification for surface finish required.