code: public void addProduction(Event event, Grammar grammar) {
  
  		containers.add(new SchemaLessProduction(this, grammar, event,
  				getNumberOfEvents()));
  		// pre-calculate count for log2 (Note: always 2nd level productions
  		// available)
  		// Note: BuiltInDocContent and BuiltInFragmentContent do not use this
  		// variable
  		this.ec1Length = MethodsBag.getCodingLength(containers.size() + 1);
  	}
docs: /*
  a leading rule for performance reason is added to the tail