Glossary
EMDMgmt
A SOFTWARE hive key written by ReadyBoost that pairs a USB device's serial with its volume label and volume serial number.
SOFTWARE\Microsoft\Windows NT\CurrentVersion\EMDMgmt has one subkey per volume ReadyBoost evaluated, named after the device path followed by <label>_<VSN in decimal>, e.g. …#CS1234567890&0#{53f56307-…}BACKUP_1016943010 (0x3C9D51A2 = 3C9D-51A2).
It directly links a device serial to a volume serial number. It is often absent on SSD systems, where ReadyBoost is not used.