require a master product key issued by each OEM maker, which is unique to the specific edition of Windows, such as Home (XP), Home Basic, Home Premium, Professional, Ultimate, etc. This SLP key is different from the product key printed on the Certificate of Authenticity affixed to an OEM assembled PC; COA product key is used in cases when Windows license stored is invalidated for some reason and re-activation is required. On February 28, 2005, Microsoft attempted to reduce software piracy by invalidating COA keys for normal online activation and requiring phone activation, but this does not apply to SLP keys which can still be used for offline activation. If the product key used for activation is lost, then product key finders, readily available on the Internet, can decrypt the key from a local installation, however only SLP keys allow the user to avoid activation upon re-installation. In the SLP 2.x implementations, BIOS report the ACPI SLIC table to the operating system. However, since SLP 2.0 was introduced, hackers have been able to create modified bootloaders based on the bootloader GRUB4DOS; these are capable of emulating an SLP text string (such as one for Dell, Acer, and so on), so it appears to be present in the BIOS. This combined with an OEM certificate and OEM product key can instantly activate a Windows Vista/7 installation illegally but also be very hard to notice. This method can also be integrated into a Windows installation disk to activate on initial boot. Another method consists of modding the BIOS to insert the SLP 2.1-2.5 table, which can be used to replace blacklisted keys, or to add the SLP table to motherboards that do not have it (such as Gigabyte). Some brand-name computers such as Dell, already have the SLP table in their BIOS, which means that using software readily available on the Internet, a pirated retail installation can be converted to OEM, and the appropriate certificate installed into the OS, which results in Windows becoming genuine. Pirates refer to copies of Windows activated in this way as Pirated Genuine Microsoft Software. With SLP 3.0, OEM SLP keys are no longer used at all. Instead, a tool is used by the OEM to embed a unique key in each computer's BIOS, making consumer versions of Windows 8 and later very difficult to pirate using the SLP insertion technique. In the SLP 3.0 implementations, BIOS