The goal of those semantics (including tags, the synonyms namespace and possibly other services in the future) is indeed to try to find common ground for all platforms who need to query items semantically - natural language assistants being the most obvious candidates - so that they could be defined once, in a generic way, avoiding platform-specific configuration whenever possible.
I think the first step would be to try to translate all types in https://github.com/openhab/openhab-alexa/blob/v3/README.md#supported-item-mapping-metadata into a combination of (unambigous) Equipment and Point/Property tags - if at all possible! The model (current version illustrated here) hasn’t been tried much so it would likely be needed to expand it.
Something like:
- PowerController.powerState >
[Power, Status] - BrightnessController.brightness >
[Light, Lightbulb](there is no Brightness tag, I don’t remember why but I remember it was discussed and it’s potentially on purpose) - ThermostatController.targetSetpoint >
[HVAC, Setpoint]
etc.
Now for the additional properties, I don’t have a solution - HABot has some too and they’re still in the habot metadata namespace, the “main” value being required but useless (it’s been replaced by semantic tags), it’s a little ugly now - note the empty string: openhab-distro/features/distro-resources/src/main/resources/items/demo.items at 4fd8a69d370868d0ad0e0544d5740d2ba968ca65 · openhab/openhab-distro · GitHub