Figure files save all information about a biped's anatomy: links, link positions, twist links, and Figure mode posture, and the scale of geometric elements. Figure (FIG) files have a .fig file name extension.
Figure files do not contain the actual biped skeleton, or any animation. They are used strictly for setting or saving a biped's pose in Figure mode.
Figure files are useful for quickly setting poses for similar or identical characters.
Clicking Load File brings the Open dialog, from which you can pick a FIG file and choose from the following twist poses options:

To save a biped's figure information to a file:
Select the biped to save.
Motion panel, turn on
(Figure Mode).
Biped rollout, click
(Save File).
Select the biped to replace with a saved figure.
Motion panel, turn on
(Figure Mode).
Biped rollout, click
(Load File).