Straight Limb corrects elbow and knee direction after AutoPlace.
When using AutoPlace, the direction of elbows and knees can often be incorrect. The Straight Leg/Arm function straightens the limbs.
For a leg, the hip joint is moved to make the knee aim straight forward. For an arm, the shoulder joint is moved to make the elbow aim straight backward.
Straight Limb straightens arms and legs by correcting elbow and knee direction after AutoPlace.