The registry value name. If the Value column is null, then the following strings in the Name column have special significance. ...

The registry value name.     If the Value column is null, then the following strings in the Name column have special significance.    +  The key is to be created, if absent upon the installation of the component.    -  The key is to be deleted, if present, with all its values and subkeys upon the uninstallation of the component.     *  The key is to be created, if absent upon the installation of the component AND the key is to be deleted, if present, with all its values and subkeys upon the uninstallation of the component.