ddh, even taking the troll's crap and response out of your post, there's stilll good fodder for discussions, that will be on topic with spacemule's thread starter.
so, here goes.
One, all arbo lines, be they used for rigging or life support, have low energy absorption characteristics. Made predominately of polyester (with some polypropylene in the inner makeup of some lines like Arborplex), they have limited stretch. Most stretch about 15% at 100% of rated tensile. Full static lines like Amsteel ll or Plasma stretch about 4% at break or full tensile. Full dynamic lines, like a nylon dock line, or a lead climbing rope for rock, will stretch up to 70%.
A full dynamic line is designed to, in an appx 10 meter drop, keep the force felt by the load at under 12 KN (kilonewtons) figure, or ~2650 lb. But it is an amount that is set that a human body can easily survive. Here's a link that describes fall factors
http://www.outdoor-tec.com/info/cont_info.htm.
Arbo lines would way exceed those loads in a long fall. For that reason, our techniques in a tree should never subject us to a long fall. And, when rigging, good technique does not include letting a load drop onto a line for more than a few feet unless the load is let run to keep the peak loads at a reasonable level.
