Tom,

I have a 10' x 12' Equinox Ultralight tarp with several nylon ties, and my belief is that these are best used to prevent the tarp from shifting around due to wind getting under the tarp when the tarp is hung on top of the ridgeline.

From an engineering standpoint, the tarp is much more uniformly supported when hung over the ridgeline, and I suspect that depending upon the angle it is anchored, one could actually tear the nylon ties from the tarp due to the weight of an accumulated snow load if the tarp was merely supported by several individual points.

The one potential downside to this method of attachment (tarp hung over the ridgeline) would be eventually wearing through the center of the tarp where it makes contact with the ridgeline, although I would expect one to tear the nylon ties from the tarp (in the case of attaching the tarp under the ridgeline) long before this would ever occur.

Jim