To add to what ladder logic stated, it is commonly used for e-stops, and typically any mushroom head functions.
I would not use the one chaka posted, as I wouldn't want to fight ewith the maintenance people what it was.
Granted, the mushroom head is not the most approriate symbol around...
Many local plants expect the machine operators to perform the electrical, mechanical, and hydraulic repairs on the machines the run.
Locally (downstate Illinois) there is a dumbing of maintenance people, specially since the wages are often below $10.00 for skilled help. Companies openly advertise electrician jobs for $6.60-8.00 hour. Was offered $10-12.00 range to be production supervisor in a local multi-million dollar plant, last spring (which also had a UL508 shop.
Even Caterpillar is outsourcing thei machinery maintenance in most of the plants, and some of the head hunter calls I recieve are unbelieveable. Specially when they ask what I want an hour.
I think Rick's idea is pretty good, and not hard to do.
regards.....casey