anchor.diff:  
   LINE_COMMENT
   	:   '--' ~[\r\n]* -> skip
  -	;+	;
  
positive.code: 
  attribute : IDENTIFIER ':' oclType '=' oclExpression;
  
  rule : calledRule | matchedRule;
  
  matchedRule : lazyMatchedRule | matchedRule_abstractContents;
  
  
negative.code: 
  libraryRef : 'uses' STRING ';';
  
  moduleElement : helper | arule;
  
  helper : 'helper' oclFeatureDefinition ';';
  
  