This standard specifies built-in safety measures aimed at preventing unexpected machine start-up (see 3.2) to allow 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;