As an added feature the disc also had an extensive interactive help database/user manual programmed onto it, as well as a dictionary of industry and Heavy Metal cultural terminology called the ""Metalopedia"". Each genuine copy of Polishing of Metal was custom engraved with the text: EMPEROR MULTIMEDIA POLISHING OF METAL CD-ROM ERC4-EB etched into the reflection hub band of the CDs. The entire capacity of the 2 CDs is used, leaving only about 1MB of free space on each, left as a buffer to allow for copy errors during the duplication process.