You might email this to ChrisA so he can update his cutting chart section from this month. There are always lots of questions about how to get tri tip in areas where it's not popular and butchers don't seem to know what it is. This type of visual reference should make life easier.
I don't remember ever having beef flap, but a butcher near me usually always has marinated ball tip alongside the tri-tip. It's a good meat for grilling, very similar to tri-tip in flavor.
Thanks K -
Ever since I moved to NY from CA 9 years ago, I've been hard pressed to find tri-tip. I try to explain it to different butchers, they look at me like I have rocks in my head.