EUROPEAN REGULATION 2006/42/CE
The new European regulation 2006/42/CE on machines has been binding since December the 29th of 2009.
Skilled worker's safety is the main motivation of this new regulation :
Safety devices must be designed to protect the technician while making it possible to access the machine and minimize as much as possible the time the machine is stopped.
Respecting these safety measures that concern fixed bonnet, adjustable, removable fastening mode on machines is mandatory.
Consult the document on the new European regulation 2006/42/CE
You can also consult Pressure Equipment Directive