This standard specifies built-in safety measures aimed at preventing unexpected machine start-up (see 3.2) toallow safe human interventions in danger zones (see Annex 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, e.g., gravity, compressed springs;? External influences, e.g. from wind;