The GMask node accepts a front and a matte clip as input. The GMask node accesses the Garbage Mask menu and includes the Tracer and Region of Interest (ROI) functions.
See Loading Garbage Mask Setups and Saving Garbage Mask Setups.
You can save and load GMask setups directly in Batch.GMask node tabs process gaps in clips set to No Media as black frames. An unconnected front clip will return an error, while an unconnected back clip will process black frames.