tutmae--CP is cervix position. I used to never be able to tell where it was because it all felt the same--but then I actually felt it at a time when I was O'ing, and can now tell the difference. When you're fertile your cervix is really high and hard to reach, so when you log signs like that along with your temps it gives FF extra data to accurately determine when you O--it's really cool! A coverline is the red crosshairs that come up on your chart showing that you O'ed--and it's very exciting when you get one!