When the PC approaches a flight of steps the foot raises to meet the stairs, and when the PC stands near a curb, one foot is raised onto the sidewalk.
Does anyone know specifically what allows (causes) this behavior? (and how to use it in custom models).

Any insight would be an appreciated head start for me. :foodndrink:

Foot IK is set up in the Body Part Data -> IT ONLY works for 3 node chains -> Thigh, Calf, Foot it will not work if you try to double chain nor will it work for chains longer the 3 nodes.

Just to add to that (even though this seems like common sense) the actual placement of said node chain is determined by the collisions of the body part and the object your standing on. Just incase that helps. :shrug:

Thank you both for the replies, that is just what I was hoping to learn.