I know, there is a documentation on the subject ID pattern at Policy of a thing,
but how can I find out, what exact subject IDs are usable with my current authentication?
Do you provide a functionality like "Who am I" ?
There is a RESTful resource, which will return the authorization subject IDs, that you can use with your current authentication.
It will return JSON with the following example payload:
The defaultSubject will be used as default subject ID when creating a new thing or policy, but you will also have access to any resource that allows access for one of the subject IDs in the subjects list.