anchor.diff:  
    ;
   
  - /** One rule of the policy. action is PERMIT by default*/
  + /** One rule of the policy. action is PERMIT by default. Target and condition are optional*/
    pol_rule
    :
    	'rule' ID 'begin'
    	(
    		'action' action_id
  - 	)? 'target' condition 'condition' condition 'end'
  + 	)?
  + 	(
  + 		'target' condition
  + 	)?
  + 	(
  + 		'condition' condition
  + 	)? 'end'
    ;
  - 
  - /** This applies to target and condition indistinctly. This is valid to use YAAL as an 
  -  * understanding tool, but it does not suffice (not easily at least) to generate XACML code
  +
  + /** This applies to target and condition indistinctly. This is valid if you use YAAL as an 
  +  * understanding tool, but it does not suffice to generate XACML code
     */
    condition
    :
  
positive.code:  	)* '"'
   ;
  
   ESC
   :
   	'\\"'
  
negative.code:  	| '<='
   ;
  
   /** Boolean values */
   bool_val
   :
   	'TRUE'
   	| 'FALSE'
   ;
  
   /** Attribute associated to a category */
   categ_attr
   :
   	ID '.' ID
   ;
  
   /** String value */
   str_val
   :
   	categ_attr
   	| STRING
   ;
  
   /** String comparator */
   str_comp
   :
   	'='
   	| '<>'
   ;
  
   /** Identifier */
   ID
   :
   	LETTER
  