A cabinet cutout lets you place a cutout with a full carcass anywhere in a cabinet.
To allow access to the CabinetCutout pages you need to check the Enable Cabinet Cutout option located in Cabinet Machining > Defined Cutouts page.
Once enabled new CabinetCutout pages will be made available.
This video shows how to use Cabinet Cutouts in CabMaster. (1:48mins)