TECO invokes the TECO text editor.  TECO is an editor capable of
 both basic editing and complex programmed string processing.

Formats

 TECO file-spec                    to edit an existing file
 TECO out-file-spec=in-file-spec   to edit from one file to another
 MAKE file-spec                    to create a new file
 MUNG cmd-file-spec                to execute a TECO command file
 MUNG cmd-file-spec text-arg       as above, but passes a text argument

As these are not built-in DCL commands, you need to enter the following
 lines in your LOGIN.COM file.

          TECO == "$SYS$SYSTEM:TECO TECO"
          MAKE == "$SYS$SYSTEM:TECO MAKE"
          MUNG == "$SYS$SYSTEM:TECO MUNG """

Additional information available:

InitializationDefaultsMemoryQualifiers

TECO decodes its commands with a built-in command decoder.  If TECO
 finds the logical name TEC$INIT, its equivalence string is assumed
 to be either a TECO macro or, if the string starts with a dollar
 sign ($), the rest of the string is assumed to be a file-spec
 containing a TECO macro to be executed every start up.  To disable
 the lookup of TEC$INIT, the qualifier /NOINI can be used.

Additional information available:

ActionsConditionsExample

Your initialization TECO macro can request the following actions
 by returning a bit encoded numeric value.

      1 => Load and start up VTEDIT.TEC (/VTEDIT)
      2 => Only inspect specified file (/INSPECT)
      4 => Inhibit TECO's memory (/NOMEMORY)
      8 => Position to VTEDIT's position marker (/FIND)
     16 => Enable scope editing SEEALL mode (/VTEDIT:SEEALL)
     32 => Enable scope editing HOLD screen mode (/VTEDIT:HOLD)
    128 => Enable scope editing scroll mode (/SCROLL)
    256 => Inhibit automatic file creation (/NOCREATE)
   4096 => Initialization is complete
   8192 => Force TECO to update TECO's memory
  16384 => Display file being edited
  32768 => Initialization used TECO's memory; TECO shouldn't

When the initialization TECO macro is executed, the following
 conditions are in effect.

  Text buffer   User's editing command
  Q-register 0  Initialization TECO macro itself
  Q-register 9  TECO's built-in command decoder data storage
  Q-register Y  TECO's built-in command decoder TECO macro

The user's editing command in the text buffer can be modified
 by the initialization TECO macro.

All other Q-registers are initially scratch and can be used or
 loaded by the initialization TECO macro; their contents will
 subsequently be preserved.

The following initialization TECO macro always disallows automatic
 file creation (256) and, for scope terminals only (512 in ET),
 enables scope editing scroll mode (128) in SEEALL mode (16) with
 immediate mode command output turned off (-1EV).

  256U0 ET&512"N Q0#128#16U0 -1EV ' Q0#4096

This initialization TECO macro would be defined as the equivalence
 string to the logical TEC$INIT as follows.

  $ DEFINE TEC$INIT "256U0 ET&512""N Q0#128#16U0 -1EV ' Q0#4096"

Your LOGIN.COM file can define the TECO command with preset qualifiers
 if desired.  The qualifiers /NOCRE, /NOINI, and /NOMEM are recognized
 by all TECO commands so that they can be preset at command definition
 time.  To disable all TECO start up actions you would use

        TECO == "$SYS$SYSTEM:TECO TECO/NOCRE/NOINI/NOMEM"

 To disable only TECO's memory you would use

        TECO == "$SYS$SYSTEM:TECO TECO/NOMEM"

 Etc.

TECO automatically remembers the file being edited.  The file's
 name is stored in a process logical called TEC$MEMORY.  If you
 invoke TECO without specifying a file-spec, TECO will read its
 memory logical and re-edit the last edited file.  TECO's memory
 feature is completely inhibited by the /NOMEMORY qualifier.

Additional information available:

/FIND/INSPECT/NOCREATE/NOINI/NOMEMORY
/SCROLL/VTEDIT

 Initially position to (find) the last marked position in the input
 file.  Position is marked with the VTEDIT ESCape-F commands.

 Simply read the file-spec, don't create a new edited copy.

 Do not automatically create a new file if the file specified by a
 TECO command doesn't already exist.

 Do not attempt to find or use TECO's private initialization
 logical TEC$INIT.

 Do not read, create, or use TECO's memory logical TEC$MEMORY.

 Automatically enter split screen scrolling mode.  The bottom 1/4 of
 the screen's lines are scrolled.  The following qualifier keywords
 can be used to initially set scrolling modes:
   /SCROLL:n
    Set the number of lines to scroll to n.
   /SCROLL:SEEALL
    Set scrolling into SEEALL mode.
   /SCROLL:n:SEEALL
    Set the number of lines to scroll to n and SEEALL mode.

 Automatically invoke the TECO keypad editor VTEDIT.  The following
 qualifier keywords can be used to initially set VTEDIT modes:
   /VTEDIT:HOLD
    Set VTEDIT into hold screen mode.
   /VTEDIT:SEEALL
    Set VTEDIT into SEEALL mode.
   /VTEDIT:HOLD:SEEALL  -or-  /VTEDIT:SEEALL:HOLD
    Set VTEDIT into both hold screen and SEEALL modes.