This case-sensitive code system http://hl7.org/fhir/uv/phd/CodeSystem/ContinuaDeviceIdentifiers defines the following codes in a Grouped By heirarchy:

Code	Display	Definition
SYSID	IEEE 11073 System Identifier	This code indicates that the identifier is the IEEE 11073 SystemId from the equivalent of the System-Id attribute
BTMAC	Bluetooth MAC address	This code indicates that the identifier is the Bluetooth MAC address, either classic or low energy
ETHMAC	Ethernet MAC address	This code indicates that the identifier is the Ethernet MAC address
USB	USB PID and VID designators	This code indicates that the identifier is the USB Pid and Vid values
ZIGBEE	ZigBee MAC address	This code indicates that the identifier is the ZigBee MAC address