anchor.diff:              
   localNumber: localDigits=LocalNumberDigits (extension | isdnSubaddress)? phoneContext parameter*;
   
  -isdnSubaddress: ';isub=' isub=Uric+;
  +isdnSubaddress: ';isub=' isub=(Reserved | ALPHA | DIGIT | Mark | PctEncoded)+;
   
   extension: ';ext=' ext=PhoneDigit+;
   
  
positive.code:         | '$' 
          | ','
          ;
          
  Uric: Reserved 
      | ALPHA_NUM 
      | Mark 
      | PctEncoded
      ;
negative.code:                           | ')'
                            ;
  
  Reserved: ';' 
          | '/' 
          | '?' 
          | ':' 
  