@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@base <http://example.com/base/> .

<Target/PK=1010> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <Target> .
<Target/PK=1010> <Target#PK> 1010 .
<Target/PK=1010> <Target#key1attr1> "K1A1" .
<Target/PK=1010> <Target#key1attr2> "K1A2" .
<Target/PK=1010> <Target#key2attr1> "K2A1" .
<Target/PK=1010> <Target#key2attr2> "K2A2" .

<Source/ID=1100> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <Source> .
<Source/ID=1100> <Source#ID> 1100 .
<Source/ID=1100> <Source#attrA> "K2A2" .
<Source/ID=1100> <Source#attrB> "K2A1" .
<Source/ID=1100> <Source#ref-attrA;attrB> <Target/PK=1010> .