7.2 Resource says
Each resource possesses a unique identifier within the system.
Either we are talking about the resource URI/IRI,
in which case "withing the system" is confusing (URIs are globally unique, not unique within a particular system)
or we are talking about internal IDs, in which case this is an implementation detail not relevant here.
I propose to replace with "Each resource is identified by a URI".
Also, we may want to position ourselves with respect to the RFC3986 vs WHATWG URL dilemma.
7.2 Resource says
Either we are talking about the resource URI/IRI,
in which case "withing the system" is confusing (URIs are globally unique, not unique within a particular system)
or we are talking about internal IDs, in which case this is an implementation detail not relevant here.
I propose to replace with "Each resource is identified by a URI".
Also, we may want to position ourselves with respect to the RFC3986 vs WHATWG URL dilemma.