T-1                             T
 
                 |                             |   
            ----------                    ----------
           | L target |                  | L target |
            ----------                    ----------
                 |                             |
                 |                             |
             -----------                  -----------
            | L surface | -------------->| L surface |
             -----------                  -----------

Substitutions currently allowed:

The surface value of each component of a feature (for instance, lip location or lip closure) my range between the previous surface value and the current target. Since this is the 3-state model, each configuration of feature values now has three versions. The version of the feature configuration (X-0, X-1 or X-2) may not change between the target and surface.

-- KarenLivescu - 03 Aug 2006