MSDM – Microsoft Digital Markerįor systems sold with Windows 8 OEM and Windows 10 OEM the 25 digit product key is not seen printed on a label but is embedded in the MSDM table of the UEFI BIOS. In order to avoid having to manually type an alpha-numeric 25 digit product key and calling Microsoft for Product Activation on every single computer they manufacture they activate their devices using a different mechanism called OEM System Locked Preinstallation (OEM SLP). Original Equipment Manufacturers like Dell preinstall Windows on millions of Devices. What is OEM System Locked Preinstallation?