Good question, wdmc. I've been meaning to do a whole thread on the tablature that accompanies my lessons. It's generated by
GuitarPro, the software I use, and there are all kinds of little symbols in there that warrant some kind of explanation. Let me get into the program and I'll do a bunch of examples, with midi files, so you can hear and see what's going on
Meantime, go back to the lesson you're talking about and have another look while playing the midi. Remember that the midi is also generated by GuitarPro, so you're hearing exactly in the midi what the tab image is showing.
I'll get that up asap.