fringleot
EDIT: a little more context.. ATEX rated zones are where there may be or always is an explosive atmosphere, this makes computer controlled systems an interesting challenge.
IMHO control systems are all distributed systems and from a creator centric perspective there is something exceptionally satisfying when part of the distributed logic and state management is in pneumatic valves.
IANAL or expert but it is also an ingenious way to get around IEC 61508 complexity. When I worked on control systems priority one for safety concerns was making logic physical (not software at all) as it is very very hard to prove software running on an OS is in any way safe - while engineering diagrams with know failure modes etc was deemed preferable (by our team at least).
again: not a lawyer or expert :)