This is where you will find the Material tags that were automatically created and assigned after clicking on either the Create Camera Mapping Tag or Create Background Object buttons. These tags simply show the links between the Camera Calibrator tag and the Material tags. For example, if the Image Scale or Image Offset values are modified in the Image tab, the corresponding parameters in the tags displayed here (Offset U/V and Length U/V) will be adjusted accordingly so the rendered image has the correct projection and background. The links can also be removed (or added) here. This is, however, rarely necessary.