Thanks for the recognition on this point. Ya, it took me a while.
I added at least 30+ minutes to my effort with a silly mistake. When I created the $Slot attribute I forgot to make it a number, rather I left it as a string. So every time I’d apply the positioning calculation it would shoot off a gazillion miles to the right. I was multiplying a number against a string. As soon as I made $Slot a number it worked. In my experience with Tinderbox, 99% of the time Tinderbox is doing exactly what you’re telling it to do; the chore is to figure out what that is. 
The other challenge I faced was with the display table. At first, the table would not show up. Hours later, with the help of Mark, “we” figured out that it was due to zooming. If you’re zoomed far out so that you can see the whole venue/slot grid then the display table is not visible. If you zoom in then it becomes visible.
Lastly, I could not figure out the time calculations in Mark’s example until I “rightly” guessed that they were arbitrary. It did not make sense to me that someone in slot one would be on for 10 min (slot (1)*10) and someone in slot 6 would be on for 6o (slot (6) *10). I asked and he confirmed that this was just an arbitrary pick. So, in my example I used a different method so there would be consistent time appears in each slot.
Oh, and I made the adornment vs. note error a few times too. 
Sure. In a typical cartesian map X to the right is positive and Y going up is positive. X to the left is negative and Y going down is negative. The polarity of Ypos in Tinderbox I reversed to negative up and positive down. To the best of my understanding, this is a mental construct used in Tinderbox due to the fact that we read (a least in the West) from top left to right and down, so positive is down and negative is up. In this case, -3 means go up -3 units from the zero axis of Y.
As a side note, if you’re in standard view one unit is equal to 64 pixels, so -3 is saying go up 192 pixels from the zero (0) axis of Y (I think this I generally correct; if not actually correct; close enough). You can check this out: Map Coordinates.
Does his help?