the yoke is the split in the power harness that ties to both sides of the limb. there are 2 types of yokes one is called a split yoke harnesswhich is split off from the harness.
the other is the floating yoke which is a short piece that is looped into the harness which can move independantly in order to balance out the preload on both sides of the limb
which IMO is the better harness system