This might be overly complicated, but my subgraph thought was something along the lines of (this example is the totally non-existent DC-as-relationships):
/graph/
/DC is a subgraph defined as:
GRAPH ?g {
<info:fedora/$pid> ?p ?o .
?p <rdfs:isDefinedBy> <http://purl.org/dc/elements/1.1/>
}
and the REST API works along the lines of:
GET /graph/
/DC STMT:=SELECT
PUT /graph/
/DC STMT:=INSERT body
POST /graph/
/DC?predicate=
&object=
&type=
STMT:=INSERT
DELETE /graph/
/DC?predicate=
&object=
&type=
STMT:=DELETE
$STMT
WHERE
in which Fedora loads the <rdfs:isDefinedBy> statements for the DC core properties, or the Fedora system properties, etc.