How do I keep track of the yardage setting on a muli-tier yardage format?
Sight-in/zero your rifle dead on at 100 or 200 yds. Black out all the visible horizontal lines on the elevation shaft except the line directly below the bottom edge of your TTC knob.
Starting at your 100 or 200 yd zero (0), one visible horizontal line equals the 1st tier (1st turn) of yardage increments. One full revolution of the knob will reveal a 2nd horizontal line which indicates the starting point of the 2nd tier (2nd turn).
At any point during shooting, by counting the visible horizontal lines on the elevation shaft, you can confirm which tier of yardage the knob is currently on. Turning the knob to the zero (0) will set the knob at the starting point of the tier.