anchor.diff:  
   // https://msdn.microsoft.com/en-us/library/ms174979.aspx
   create_table
  -    : CREATE TABLE table_name '(' column_def_table_constraint (',' column_def_table_constraint)* ','? ')' (ON id | DEFAULT)? ';'?
  +    : CREATE TABLE table_name '(' column_def_table_constraint (','? column_def_table_constraint)* ','? ')' (ON id | DEFAULT)? ';'?
       ;
   
   // https://msdn.microsoft.com/en-us/library/ms187956.aspx
  
positive.code:     | RELATIVE
      | REMOTE
      | REPEATABLE
      | ROOT
      | ROW
      | ROWGUID
  
negative.code:     | op=('+' | '-') expression                                #unary_operator_expression
      | expression op=('+' | '-' | '&' | '^' | '|') expression   #binary_operator_expression
      | expression comparison_operator expression                #binary_operator_expression
      ;
  
  constant_expression
  