In reply to elliot.baker:
>"if there are "double belay bolts" at the bottom of a climb to prevent the belayer from falling, how should you use these?"
1) Belayer ties in to dead end of the rope with normal fig8 knot as if he was going to lead.
2) Clove-hitch belayers rope to a screwgate on first bolt.
3) Adjust to desired length appropriate to the stance.
4) Leave a small loop of slack before tying a second clove-hitch to a screwgate on second bolt.
5) Clip belayers tie-in rope loop with a screwgate.
6) Clove-hitch returning rope (from the second bolt) to the screwgate in the belayers tie-in rope loop.
7) Adjust to desired length appropriate to the stance and equalized with other bolt.