Hello,
Firstly as a sidenote, Supported/Conflicting is checked only one-way, if say devices A and B are enabled and say B has ConflictingDevice "C", and device C doesn't list anything, enabling of C is possible (and after that disabling C is not possible before B is disabled first).
Now, looking at the way SupportedDevice and ConflictingDevice are implemented in ucm and I came to following conclusion:
If no SupportedDevice or ConflictingDevice: All devices and combinations are compatible, so implicit "SupportedDevice ALL".
If SupportedDevice is listed: Device can be enabled as long as at least one enabled device is in SupportedDevice list.
If ConflictingDevice is listed: Device can be enabled if none of active devices are in ConflictingDevice list (noting aforementioned limit in checking this)
This is at least how I figured all combinations of multiple devices can be defined with only zero or one either SupportedDevice or ConflictingDevice entry per device.
Did I understand this right?