A rundown on what I think are relevant things about SCAP's Asset Identification standard to this group:
It provides a naming scheme for the types of objects listed in section 5.3 (person, org, system, software, database, network, service, data, computing device, circuit, website)
Same section describes the following types of identifiers:
literal identifiers are pre-defined values that can define an asset, e.g. MAC address
synthetic identifiers are used when an identifier is assigned to the asset, e.g. hostname or IP address
relationship identifiers (!) where there is information that relates an asset to another asset
I have some quibbles with the document but overall it's very good. It focuses on the IT-sphere rather than the entire IOT but with protocol extensibility it could be a good approach to identification. Discovery is still the harder problem.
Attached is my diagram representing the data model used by the standard.