The BNF Syntax at [1] seems to exclude the definition of uri_ref_esc which is used to define: value ::= uri_ref_esc | literal_value [1] http://open-services.net/bin/view/Main/OSLCCoreSpecQueryDRAFT?sortcol=table;up=#oslc_where Thanks, Steve Speicher | IBM Rational Software | (919) 254-0645