Funny, I use exactly the same shorthand in my log.
Like Leeroy said, a classic Bill Drill is shot at 7 yards, from a surrender start, draw and fire 6 rounds into a USPSA target. Technically you have to get all six hits in the A-zone for it to count.
Depending on how you approach the Bill Drill, you can use it to practice getting a bunch of different skills. I like to start out by shooting a few (5-10) Bill Drills with the par timer set to 2.2 seconds (or whatever time you *know* you can get six solid Alphas in,) with my focus on getting a perfect rock-solid grip from the drawstroke. The six fairly quick shots help ensure that my awesome grip won't break down under recoil. Next, I shoot a few Bill Drills literally as fast as I can pull the trigger, not worrying about hits overmuch, in order to work on my trigger speed. Finally, I'll set the par timer to a time that I can just barely stretch to meet (for me, around 1.9 seconds) and focus on watching the front sight lift on all six shots.
I also often shoot Bill Drills at 15 and 25 yards. I find that I tend to slow down too much for distant targets. Bill Drills against fairly strict time limits are a good way to fix this tendency.
A good Bill Drill time is 2.0 seconds at 7 yards, from an unconcealed OWB holster. Top shooters should be hitting it in around 1.6-1.7 seconds.