anchor.diff:     ;
   
   typeDefinitionPart
  -   : TYPE typeDefinition (SEMI typeDefinition)* SEMI
  +   : TYPE (typeDefinition SEMI)+
      ;
   
   typeDefinition
  
positive.code:    ;
  
  variantPart
     : CASE tag OF variant (SEMI variant | SEMI)*
     ;
  
  tag
  
negative.code:    ;
  
  fieldList
     : fixedPart (SEMI variantPart)? 
     | variantPart
     ;
  
  fixedPart
  