This Standard specifies designed-in means aimed at preventing unexpected machine start-up (see Clause 4.2) to allow safe human interventions in danger zones.Examples of tasks which can require the presence of persons in danger zones are listed in Appendix A.This Standard applies to unexpected start-up from all types of energy source, i.e.power supply, e.g. electrical, hydraulic, pneumatic;stored energy due to, for example, gravity, compressed springs; andexternal influences, for example, from wind.