A WWID (World Wide Identifier) number is used to keep track of storage devices. If you come across one in metadata you may be able to use it to hunt down the type of device being referenced. It may also be referred to as the WWN, the World Wide Name. An organization unique identifier (OUI) may comprise part of the WWID. A list of OUIs is located here:

So this example for a Cisco device:

. . . can be cross-referenced with this information: