code: public void toRSL(StringBuffer buf, boolean explicitConcat) {
  	buf.append("( ");
  	buf.append( getAttribute() );
  	buf.append(" = ");
  	Iterator iterator = values.iterator();
  	Binding binding;
  	while(iterator.hasNext()) {
  	    binding = (Binding)iterator.next();
  	    binding.toRSL(buf, explicitConcat);
  	    if (iterator.hasNext()) buf.append(" ");
  	}
  	buf.append(" )");
      }
docs: Produces a RSL representation of this relation.
  
  @param buf buffer to add the RSL representation to.
  @param explicitConcat if true explicit concatination will
  be used in RSL strings.