This International Standard defines the GRAFCET specification language for the functional description of the behaviour of the sequential part of a control system. This standard specifies the symbols and the rules for the graphical representation of this language, as well as for its interpretation. This standard has been prepared for automated production systems of industrial applications. However no particular area of application is excluded. Methods of development of a specification that makes use of GRAFCET are beyond the scope of this standard. One method is for example the "SFC language" specified in IEC 61131-3, which defines a set of programming languages for programmable controllers.