BOB has many meanings. Among them, "Bail/Bug Out Bag".

Now, as for what BOB's mission is, that varies widely, and we've had long debate/discussion on that. The mission I define is: get out of Dodge, and self sufficent (including water) for X number of hours. The number of hours is based on your estimate of how long you think it will take you to get to where you are going, becuase in my humble (?) opinion, the first thing you need to do when developing a bug out plan is know where you are bugging towards so you can dig in once you are there. (The first decision is when to bug out vs dig in in place, with the zeroth decision being to actually make up a plan.)

That could be 72 hours, that could be 120 hours, going up. My kind of BOB isn't terribly long term, becuase my self sufficency includes water, unless he's a big, heavy bruiser with half or more the mass being water. But he is designed with you heading for your destination on FOOT. Don't count on your car/motorcycle/horse, to many bad things can happen there. Every 4-5 miles you make in a car is an hour of free time credited to BOB, but if you decide to bug out at work, leave, dash home, grab BOB and find your chariot has been stolen/lit on fire/spat a cylinder head through the hood, you are still good to go. Just at a slower pace.

That's why my BOB always has a side kick, the walking stick.

As for what goes in, what do you think you'd need to last X-number of hours? Change of clothes, couple changes of socks, food, rain gear, shelter material, water, first aid kit, and the basics of a survival kit. That type of thing varies from person to person, depending on their location/climate, anticipated reasons for bugging out, thier preferences, skill level, and budget.

Now, I like to layer BOB. BOB carries a lot of stuff, including what I call a ditch kit which is either worn seperately or on BOB. That is becuase there might be a scenario where you have to dump BOB. The ditch kit is the ONE thing you take off your buddy if you have to leave him behind, and you have to be able to execute BOB and tear the ditch kit out/off his carcass in under 60 seconds (an arbitrary limit). With the ditch kit, you would have some water, some food, rudimentary shelter, a basic FAK, all the stuff that makes up a light weight survival kit. Plus your ID, data back ups (CD full of scanned paper work like insurance policies), perosnal meds and the universal lubricant (money).

Of course, you already have the basics in your PSK, which is in your pocket, and your belt order in case you have to dump the ditch kit. And in a very worse case, and you've literally lost your pants, you've at least got the contents of your brain.

BTW, if you have a number of similar packs, be able to ID BOB from his siblings at a glance. Don't trust storing them apart. That could be he has the green paracord wrapped around his frame, not the black, or he has red zipper pulls, or any of a number of ideas. But if you have BOB embroidered on him, don't be suprised if people think you are him.