Hello. I'm designing device arrival/departure notification routines for my
HID device, and since any number of devices could be attached to the host, I
need a way to differentiate between devices in my departure notification.
Say if 3 devices were present, and their context stored away, I need to know
which one of the 3 devices had departed, so I can clean up its context. In
other words, I need a property which uniquely identifies each device.
Unfortunately, there is no unique serial number for each device. I observed
that kIOHIDLocationIDKey is unique for each device. But what does this
property mean? Is it guaranteed to be unique for each device, no matter
what the topology?
