Pre Render MEL
Post Render MEL

3Delight for Maya lets you specify MEL scripts that will be executed before and/or after each Shadow Map is rendered. More precisely, the Pre/Post scripts will be executed just before the FrameBegin RIB statement and/or just after the FrameEnd RIB statement. These two attributes are empty by default. The following variables are automatically defined in the context of the MEL scripts:

string $shape_path    → Contains the current light shape path.