anchor.diff:      : IDENTIFIER_
       ;
   
  +
  +
  +
  +
  +
  +
  +
  +
  +
  +
   columnClauses
  -    : opColumnClause+ | renameColumnSpecification
  -    ;
  -
  -opColumnClause
  +    : operateColumnClause+ | renameColumnClause
  +    ;
  +
  +operateColumnClause
       : addColumnSpecification | modifyColumnSpecification | dropColumnClause
       ;
   
  
positive.code:     : (columnName | attributeName) (DEFAULT expr)? (inlineConstraint* | inlineRefConstraint?) | outOfLineConstraint | outOfLineRefConstraint
      ;
  
  columnProperties
      : columnProperty+
      ;
  
  columnProperty
      : objectTypeColProperties
      ;
  
  objectTypeColProperties
      : COLUMN columnName substitutableColumnClause
      ;
  
  substitutableColumnClause
      : ELEMENT? IS OF TYPE? LP_ ONLY? dataTypeName_ RP_ | NOT? SUBSTITUTABLE AT ALL LEVELS
      ;
  
  
negative.code:     : CHECKPOINT NUMBER_
      ;
  
  renameColumnClause
      : RENAME COLUMN columnName TO columnName
      ;
  
  