Let's say my camp is halfway between E and F, halfway between 9:00 and 9:30 — right in the middle of the block.
Is that:
- E @ 9 /*\>
- E @ 9:30 </*\
- F @ 9 )*(>
- F @ 9:30 <)*(
I think none of these describe where my camp is because they also identify the four corners on the outside of the block. Plus, does the ">" descriptor mean "the location is greater than the identified clock position," "the identified clock position is greater than the location," "to the right as facing [man/mountain]", or "further away from center camp"? That just dawned on me as I was trying to list things out correctly after having been away from the instructions for a few days.
But if you said something like E:M @ 9:15 or E:30 @ 9:15 or E.5 @ 9:15, then you're right on it. I prefer the alphabetic version E:M but that might lead to confusion when it's E:C, for instance — does that mean halfway further (based on A-H) or 1/10th the way in (A-Z)?
Of course New Math solves all this with A-Z meaning digits 0-25. E-B/C means "E and a half" ... of course, so does E-J/Y or E-D/H. And then E.M is also possible: right between E.LZ and E.MA.
I suspect that your best bet, Donna, would be to enumerate all the possible ways to make unambiguous addresses. But that's just me ... making lists and organizing things is so fucking exciting. You should have seen the minimum/maximum itinerary for the trip across the country that still makes my girlfriend's eyes roll.
which direction I was headed in - the clock designations 9:00+ and 9:00- are very logical but personally I would have to figure it out which way is up the clock and which way is down the clock. But on the other hand, I generally can remember my right from my left. 
And, more importantly, if the camp has a sign or other marker, then the any close address will do - it will get you close enough to the camp to be able to look around and see their sign.
