The Referencing section of the dialog provides some information on the current referencing state of the chosen point. These numbers are updated as the algorithm runs.
After automatic referencing you can undo the referencing by hitting the "Unreference previous references" button. The useful thing here is that this "unreference" ability is available even after this dialog is closed. In fact you can do an automatic reference, close this dialog, process the project and then still come back and unreference all the automatically referenced items. If you close the project or PhotoModeler the ability to undo the automatic references is lost.
Note: "Unreference previous references" is not a true “undo”. It restores the previous reference state (which marks were associated with which 3D objects), but leaves the items’ properties in their changed state. That is, if the automatic referencing named some points to 'ar' or changed a point’s material or layer, then these changes are not reversed.