Based upon the details I can find in a couple Door Game source files from March 1996, there was a ZIP comment specification. It was plain 8bit ASCII, not embedded ANSI or AVATAR colors. The generator for a couple of these doors, generate a 78 column file, with up to 23 lines.

From one product I bought:

        McSoft Corp. Presents
  
                       The Ultimate BattleShip Game!
  
                  . .
              `.. .  .             /======|
            ` ` .' '.        _____/_______|
             `.`'.'.  ______/             |     ||===||
              ``'.   /                    |     ||===||
          <----''-----------------------------------------|
           \   ' `                                        |
            \                                             |
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                     BATTLE SHIPS DELUXE V3.00 BETA