The "Executive" (or "Exec"; aka "Protocol-A") protocol was developed as a proprietary standard by Mars (MEI) for communications with payment systems (coin-mechs, etc) in vending machines.
It is now something of a de facto standard, but is the specification now published anywhere? Or do I have to contact MEI?

Unfortunately, this is one of those cases where Googling just gets swamped in references to vending machines, coin-mechs, etc, that support "Exec" and I haven't yet found a proper specification! :-(

Yes, there are brief mentions at http://www.bonusdata.ch/vending/A...ending.htm and http://www.eva.be/standards...update.pdf - but no spec.

Looks like a call to MEI, then?