RDF (and Oracle's RDF offering) in general allows associating as many attributes as you need to nodes in the graph. You are right in saying that those attributes are
modeled as RDF resources (nodes). This promotes sharing of resources.
e.g. The first two triples associate the same street resource with two individuals. The third triple
provides some descriptive information about this street resource.
<urn:John> <urn:livesOnStreet> <urn:StreetXYZ>
<urn:Mary> <urn:livesOnStreet> <urn:StreetXYZ>
<urn:StreetXYZ> rdfs:comment "Sunset Rd. .... "
It is usually up to an application to determine how many attributes to use. The underlying RDF graph model supports
multiple attributes and Oracle's RDF implementation supports multiple attributes.
It is also possible to store attributes in a separate relational table and use a SQL to join the graph query results
with your relational data.
Hope it helps,