yep, seen that. it's in Patch > Device List > RDM, right?
there is RDM-enabled equipment that doesn't output anything and doesn't need a start address. but still it is a valid rdm-device and can be configured through the rdm functionality of eos.
i think an example would be City Theatrical's Show DMX Baby which is a rdm-enabled wireless dmx-transmitter. it doesn't take a start address, it's not a fixture, but still it takes some configuration through rdm.
if you select the device by typing Address 0 Part 2 Enter it should list everything that this device is reporting through rdm, like a nyme and a type, information from sensors and status as well as dropdown lists of stuff you can change (the lines with a > in front of them). and of course there is the Identify function. i think some of those even flash a status led to identify themselves.
you can't give those address zero devices a fixture type because you can't patch them. i think the only place where you can get to their settings is in Patch > Device List > RDM or maybe (haven't tried that) in Live > About Address 0.
What fixture(s) is giving you the Address 0 (just curious)?
Address 0 will also represent the main set of device information for a fixture will multiple individually addressed parts. An example is the ETC SmartBar2 fixture. This will appear in the device list addressed at 0 for the main device information and then have either 2/4/6 individually addressed dimmers (sub-devices) listed as well.
Address 0 devices can't be patched and are only there to show/edit the main device properties. It is the sub-devices that you can patch.
