Viewers...
 This command is used  to  create  and  maintain  the  viewer
 extension file, which associates different viewers with file
 extensions. This feature allows you to use different viewers
 to view files with different extensions.

 Lines in the  VCVIEW.EXT  file consist of the extensions and
 the  commands  to  view  files  with that extension (usually
 these commands are viewers):

        +---- Extension
        |               +--- Insert file name and extension
        .               .
       dbf: dbview.exe !.!
            @ cls
            +------------+
               Commands

 tells the Commander to run Data Base viewer when  you  press
 F3 on a file that ends in .dbf (such as "somename.dbf"), and
 then to clear the screen.

 A comment line should have ' character in the first column.

 You can type @ character before  any  DOS  command to cancel
 output of the prompt and the command line.

 Here are all the ! arguments that you can use in commands:

   Argument     What                             Example
   --------     ---------------------------      ------------
   !.!          File name with the extension     filename.ext
   !            File name, without extension     filename
   !:           The current drive letter         A:
   !\           The current page                 \PATH
   !!           Insert the `!' character         !

   Notes:
     .  You can use ":" to match any file without extension.

     .  You can use DOS wildcard characters. So, for example,
        "*:" will match any extension.

     .  There  are  two  types of viewer extension file: Main
        and Local. The main extension file is stored  in  the
        same  directory as the  Commander (or  the  directory
        pointed to by the VC environment variable). The local
        extension file is an extension file  in  the  current
        directory. This  allows  you  to  have  a  number  of
        extension files in different directories.

     .  There is  an  alternative  format  to  load  standard
        viewers. The extension  file  item  must  consist  of
        the extension and the viewer's name  with  extension.
        You  should  not  use @ character  and  any  of the !
        arguments.  Specify  the drive letter and the path if
        the  viewer  is  located  in  a  different  drive  or
        directory than the Commander. For example:
                   dbf: c:\progs\dbview.exe

     .  Press Alt+F3 to use the built-in viewer.

     .  Option  Alternative viewer  in  Advanced options menu
        Options  allows  you  to  swap functional keys F3 and
        Alt+F3.