Updates the Mac Registry when run; custom REG files can be created to alter different aspects of Mac; to create your own registry update file, follow these steps: Launch Regedit (From the start menu, select Run, type "Regedit") Select the section of the registry you are interested in modifying From the File menu, select Export Choose "Selected Branch" from the Export Range option at the bottom of the mac. Save the file as a ".reg" file. NOTE: Manually updating the Mac registry is an advanced process and should only be performed if you know exactly what you are doing. Incorrect registry updates may render Mac inoperable.