anchor.diff:  */
   category_header returns [String category]
     : CATEGORY_HEADER category_header_val
  -    {$category = "\"category\":{" + $category_header_val.category + "}"; }
  +    {$category = "{\"category\":{" + $category_header_val.category + "}}"; }
   
     | CATEGORY_HEADER multi_cat1 = category_header_val
  -    {$category = "\"category\" : [{"+$multi_cat1.category + "}";}
  +    {$category = "{\"category\" : [{"+$multi_cat1.category + "}";}
       (
         COMMA multi_cat2 = category_header_val
         {$category += ", {"+$multi_cat2.category + "}";}
       )+
  -    {$category += "]";}
  +    {$category += "]}";}
   ;
   category_header_val returns [String category]
     : term_attr scheme_attr class_attr (title_attr | rel_attr | location_attr | cat_attributes_attr | action_attr)*
  
positive.code:   : LINK_HEADER single_val = link_header_val
      {$link_header = "{\"link\":{" + $single_val.link_header_val + "}}";}
  
    | LINK_HEADER link_header_val (COMMA link_header_val)+
      {;}
  ;
  link_header_val returns [String link_header_val]
    : OPEN_PATH link_path_val CLOSE_PATH rel_attr
  
negative.code: 
  occi_headers returns [String header]
    :
    {$header = "[";}
    (
  	    category_header {$header += $category_header.category;}
  
  	  | link_header {$header += $link_header.link_header;}
  
  	  | attribute_header {$header += $attribute_header.attribute_header;}
  
  	  | location_header {$header += $location_header.locations_val;}
    )+
    {$header += "]";}
    EOF
  ;
  
  