Retargeting allows you to transfer any type of animation between characters, regardless of their size or proportions. Retargeting involves first tagging (identifying) the elements of a rig, then transferring animation from another rig or a mocap data file to the rig. The animation is retargeted to the new rig as it's transferred. The retargeted animation is "live" on the rig, controlled by the retargeting operators that live on the tagged rig elements. Because of this, you can adjust the animation on the rig at any time so that the motion is exactly as you like. If you want to commit the retargeted animation to fcurves, you can plot it on the rig.
While you can retarget any type of animation between characters, it is especially useful for reusing motion capture data to animate many different characters with the same movements, such as you would for a game. For example, you can reuse a basic run mocap file for many characters and then adjust the animation for each one as you like by adding offsets in different animation layers. Using the retargeting and layering tools in Softimage, you can quickly test out many variations of animation on the characters.
Using the commands in the Tools 
MOTOR menu on the Animate toolbar, you can perform all of these steps. See the corresponding section for information about each
one:
Tag rig elements so that animation can be retargeted onto them — see Tagging a Rig's Elements.
Retarget animation from one rig to another — see Retargeting Animation from Rig to Rig.
Retarget animation from BVH or C3D mocap files to a rig — see Retargeting Mocap Data from C3D or BVH Files to a Rig.
Adjust the retargeted animation on the rig, such as by setting position and rotation offsets for the whole rig or just certain elements — see Adjusting the Retargeted Animation on a Rig.
Save any type of retargeted animation in a normalized motion format (.motor file) so that it can be loaded and retargeted on any rig. This makes it easy to build up libraries of animation that can be used across all your rigs — see Saving Animation Data in Normalized Motion (.motor) Files.
Load normalized animation files on any tagged rig — see Applying Normalized Motion (.motor) Files to a Rig.
Plot the retargeted animation on a rig into fcurves so that you can edit the animation — see Plotting Retargeted Animation on the Rig.
Before you start tagging the character elements or retargeting animation, make sure that the skeleton or rig is in a model. Retargeting can work only within model structures.