1.DBG> SHOW MARGINS
      left margin: 1 , right margin: 255
      DBG>

      This command displays the default margin settings of 1 and 255.

    2.DBG> SET MARGINS 50
      DBG> SHOW MARGINS
      left margin: 1 , right margin: 50
      DBG>

      This command displays the default left margin setting of 1 and
      the modified right margin setting of 50.

    3.DBG> SET MARGINS 10:60
      DBG> SHOW MARGINS
      left margin: 10 , right margin: 60
      DBG>

      This command displays both margin settings modified to 10 and
      60.