anchor.diff:    TOKEN
   ;
   
  +attributes:
  +  CAT_ATTR_SEP ATTRIBUTES_ATTR VAL_ASSIGN QUOTE attributes_names QUOTE
  +;
  +attributes_names:
  +  attribute_attr_name (attribute_attr_name)*
  +;
  +
   link_header:
     LINK_HEADER  link_path rel (self | link_category)* attributes_attr?
   ;
  
positive.code:   CLOSE_PATH = '>';
  }
  
  
  // ---------------------------------------- 
  // ---------- Category attribute ---------- 
  // ---------------------------------------- 
  
  /*
  ABNF representation of category from the http rendering specification
  
negative.code: scheme:
    CAT_ATTR_SEP SCHEME_ATTR VAL_ASSIGN QUOTE scheme_val QUOTE
  ;
  scheme_val:
    URI
  ;
  
  