[_Jim]

I'm taking it to be ice - that hit the leading edge of the wing in the LESS (Leading Edge Structural Subsystem) area and perhaps a tile or so as well ... damage to the LESS can also result in catastrophic failure of the shuttle on reentry due to plasma (hot gases) making their way in to attack the wing spars (constructed of aluminum) ...

[bonesmccoy]

WoW!

that's one heck of a pdf document!

Now I can understand why the space agency was having a debate about retirement of OV-102.

Your link shows:
1. OV-102 has a design difference from the rest of the fleet. The leading edge of the wing is structurally different in design.
2. OV-102 leading edge surfaces may behave differently from the rest of the fleet under circumstances of overheating.

I wish I had the STS-107 temperature data. You could plot the temperature data on a grid of the wing and identify where the TPS was lost.