A new international standard has been published for the design, manufacture, and testing of electro-sensitive protective equipment for safeguarding machinery. The guideline, issued by the IEC, covers opto-electronic devices, such as light curtains and light-beam devices. Many machines have such devices to sense whether a person is hazardously close. The new standard covers only the functioning of the electro-sensitive protective equipment and how it interfaces with the machine. It does not specify the dimensions or configurations of the detection zone and how it relates to hazardous parts for any particular application. Nor does the standard specify what constitutes a hazardous state for any machine.