DuckCorp Dico

Found one definition

1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   flag
      1. <programming> A variable or quantity that can take on one
      of two values; a bit, particularly one that is used to
      indicate one of two outcomes or is used to control which of
      two things is to be done.  "This flag controls whether to
      clear the screen before printing the message."  "The program
      status word contains several flag bits."  See also hidden
    flag, mode bit.
      2. command line option.
      [Jargon File]
      (1998-05-02)