PropertyFunctionRegistry reg = PropertyFunctionRegistry.chooseRegistry(context) ;
PropertyFunctionFactory f = reg.get(procId.getURI()) ;
PropertyFunction pf = f.create(procId.getURI()) ;
pf.build(subjArg, procId, objArg, execCxt) ;
//Make wrapper
return new ProcedurePF(pf, subjArg, procId, objArg) ;
}