IEC 61131-1:2003 applies to programmable controllers (PLC) and their associated peri-pherals such as programming and debugging tools (PADTs), human-machine interfaces (HMIs), etc., which have as their intended use the control and command of machines and industrial processes. It gives the definitions of terms used in this standard. It identifies the principal functional characteristics of programmable controller systems. This second edition cancels and replaces the first edition published in 1992 and constitutes a technical revision. This bilingual version (2012-05) corresponds to the monolingual English version, published in 2003-05.