I did some ski patrolling a few years ago and the term "Out Of Bounds" was part of everyday conversation. In ski-speak, anything past the official boundaries of the ski area was out of bounds. Joe skier wasn't supposed to go there, but if he did, he should expect to take care of himself. We were always rounding up the dumbasses who weren't prepared.
In cycling, there are no signs or caution tape, but I've loosely come to define 'out of bounds' as anywhere where a) you don't have cell reception, and b) human contact is scarce. Places where you might be totally on your own, in other words.
My solo trip into the CDANF this summer forced me to figure out how I think I should prepare for that situation. Mine might be a good plan or not, but at least it's a plan. There are multiple aspects, but as far as being able to keep my bike pedal-able, it all boiled down to this baggie:
It's the hardware in addition to what you would normally pack in your seat bag:
-Cable ties, in 2 sizes
-Rubber bands (you never know)
-Cleat (do you know how screwed you would be?)
-A bottle 'o screws, nuts and washers
-Fiberfix spoke repair kit
-Super minimal first aid kit
The baggie weighs 9 ounces and having it all in one place that you can just toss in your pack is pretty cool. All in all, shit you are very, very unlikely to ever need. But also shit that, given the option of waiting several hours for a lift, might start to look pretty damn attractive. And keep you from being the latest laughingstock of your local search and rescue crew.