anchor.diff:      ;
   
   literals_
  -    : number
  -    | string
  +    : numberLiterals
  +    | stringLiterals
       | booleanLiterals
       | nullValueLiterals
       | bitValueLiterals
  
positive.code:     ;
  
  orderByItem
      : (columnName | number | expr) (ASC | DESC)?
      ;
  
  dataType
  
negative.code:     : QUESTION_
      ;
  
  numberLiterals
     : NUMBER_
     ;
  
  stringLiterals
      : STRING_
      | characterSet_? STRING_ collateClause_?
      | IDENTIFIER_ STRING_ COLLATE (STRING_ | IDENTIFIER_)?
  