well... the diagram is below... but I would be willing to bet that it isn't going to make a whole ton of sense if you can't trace the vacuum line to its source and figure out what it does. And trying to figure out where every single vacuum line goes just to figure out one blocked line is a little ridiculous, not like there are handfuls of different lines on both sides of the engine bay.
Why don't you take a little bit different approach and figure out what the line might be/might be for... detailed pictures would be a big help. But at the very least, a detailed description of where the line is, and where it goes would be a good start.
Many of the vacuum lines are related to emissions systems and can be blocked and/or bypassed without any real issue. Many times, someone will find an open vacuum line and instead of finding where it goes and fixing it, they just block it off. The engine is running, so they think "why waste the time fixing something that doesn't really matter" so they just stick a bolt in the end of it and leave it alone.