String prefix = peekToken().getImage() ;
nextToken() ;
if ( ! lookingAt(IRI) )
exception(peekToken(), "@prefix requires an IRI (found '"+peekToken()+"')") ;
String iriStr = peekToken().getImage() ;
IRI iri = profile.makeIRI(iriStr, currLine, currCol) ;
profile.getPrologue().getPrefixMap().add(prefix, iri) ;
nextToken() ;
expect("PREFIX directive not terminated by a dot", DOT) ;
}