Even better, when designing a firing system, if there is no electrical difference between an "in" and "out" socket (as in Sam Woodward and many others where boxes are simply paralleled)
don't use different genders! Then it doesn't matter which way round a cable goes!
I've been in a "five minutes before firing you go to plug the cables in to the desk and wonder why the two connectors you're trying to mate are the same gender... arrrrghhh!" situation too
Cheers,
Robin.
P.S. for labelling boxes I find the metallic type dymo tape lasts reasonably well in field conditions.