You can mirror pose interpolators, poses, and their associated pose shapes using the Pose Editor. Mirroring makes the selected item appear in symmetry on the base object according to the axis that you choose. This helps you save time when you need the same corrective shapes done on both sides of a character: make the changes on one side, then mirror it to the other.
If you mirror a pose interpolator (such as R_Arm_Upr), a new corresponding one is created (such as L_Arm_Upr), along with its poses and associated pose shapes. If you mirror a pose, a new corresponding pose and its associated pose shapes are created inside the corresponding pose interpolator. A new corresponding pose interpolator is created if one doesn't already exist.
If symmetry in Maya is not already on, it is activated for the mirror operation, but then turned off when you're done. If symmetry is on, its settings are ignored during the mirror operation, and restored after mirroring is finished.
To mirror pose interpolators or poses
If you select pose interpolators, all their poses and associated pose shapes are mirrored.
If you select poses, only they are mirrored, along with their pose shapes.
By default, R_ is displayed as the Source string since most modelers work on the right side of a model and then mirror or copy to the left side.
The mirrored pose interpolators and poses will be named using the Target substring.
Select the direction and symmetry axis to be used for mirroring the target shape.
If there is no symmetry seam already defined for the object, you are prompted to select an edge as the mirror axis (Edge mode is automatically enabled so you can click the edge).
Store topological symmetry seam edges: Available only if you select Topology. This option stores the last-defined edge as the symmetry seam used for this blend shape deformer. If you mirror a target shape that belongs to another blend shape deformer, you are prompted to select an edge again.