Use Figure mode to fit a biped to the mesh or mesh objects representing your character. Leave Figure Mode on when you attach the mesh to the biped with Physique. Figure mode is also used to scale a biped with a mesh attached, to make biped "fit" adjustments after Physique is applied, and to correct posture in motion files that need a global posture change.
When Figure Mode is turned on, the biped jumps from its animated position to its Figure Mode pose. Animation is preserved when you exit Figure mode.
All of the parameters on the Structure rollout are active in Figure mode.