Escape sequence
A special sequence of ASCII characters beginning with the escape character (ESC) used to send special text-formatting or editing commands to terminals. See also: [ASCII](https://vt100.net/docs/tp83/glossary.html#a09)

A line discipline (LDISC) is a layer in the terminal subsystem in some Unix-like systems. 

The terminal subsystem consists of three layers: 
    * the upper layer to provide the character device interface, 
    * the lower hardware driver to communicate with the hardware or pseudo terminal, 
    * the middle line discipline to implement behavior common to terminal devices. 

Definitions
-----------

Many controls use parameters, shown in italics.  If a control uses a
single parameter, only one parameter name is listed.  Some parameters
(along with separating ;  characters) may be optional.  Other characters
in the control are required.

C    A single (required) character.
Ps   A single (usually optional) numeric parameter, composed of one or
     more digits.
Pm   Any number of single numeric parameters, separated by ;  charac-
     ter(s).  Individual values for the parameters are listed with Ps .
Pt   A text parameter composed of printable characters.


Control Bytes, Characters, and Sequences
----------------------------------------

ECMA-48 (aka "ISO 6429") documents C1 (8-bit) and C0 (7-bit) codes.
Those are respectively codes 128 to 159 and 0 to 31.  ECMA-48 avoids
referring to these codes as characters, because that term is associated
with graphic characters.  Instead, it uses "bytes" and "codes", with
occasional lapses to "characters" where the meaning cannot be mistaken.

Controls (including the **escape code 27**) are processed once:

---- snip ----

C1 (8-Bit) Control Characters
-----------------------------

The xterm program recognizes both 8-bit and 7-bit control characters.

It generates 7-bit controls (by default) or 8-bit if S8C1T is enabled.

The following pairs of 7-bit and 8-bit control characters are equiva-
lent:

---- snip ----
ESC [
     Control Sequence Introducer (CSI  is 0x9b).
---- snip ----
ESC ]
     Operating System Command (OSC  is 0x9d).


---- snip ----


Non-VT100 Modes
---------------
Tektronix 4014 Mode
-------------------

Most of these sequences are standard Tektronix 4014 control sequences.
Graph mode supports the 12-bit addressing of the Tektronix 4014.  The
major features missing are the write-through and defocused modes.  This
document does not describe the commands used in the various Tektronix
plotting modes but does describe the commands to switch modes.

Some of the sequences are specific to xterm.  The Tektronix emulation
was added in X10R4 (1986).  The VT240, introduced two years earlier,
also supported Tektronix 4010/4014.  Unlike xterm, the VT240 documenta-
tion implies (there is an obvious error in section 6.9 "Entering and
Exiting 4010/4014 Mode") that exiting back to ANSI mode is done by
resetting private mode 3 8  (DECTEK) rather than ESC ETX .  A real Tek-
tronix 4014 would not respond to either.

BEL       Bell (Ctrl-G).
BS        Backspace (Ctrl-H).
TAB       Horizontal Tab (Ctrl-I).
LF        Line Feed or New Line (Ctrl-J).
VT        Cursor up (Ctrl-K).
FF        Form Feed or New Page (Ctrl-L).
CR        Carriage Return (Ctrl-M).
ESC ETX   Switch to VT100 Mode (ESC  Ctrl-C).
ESC ENQ   Return Terminal Status (ESC  Ctrl-E).
ESC FF    PAGE (Clear Screen) (ESC  Ctrl-L).
ESC SO    Begin 4015 APL mode (ESC  Ctrl-N).  This is ignored by xterm.
ESC SI    End 4015 APL mode (ESC  Ctrl-O).  This is ignored by xterm.
ESC ETB   COPY (Save Tektronix Codes to file COPYyyyy-mm-dd.hh:mm:ss).
            ETB  (end transmission block) is the same as Ctrl-W.
ESC CAN   Bypass Condition (ESC  Ctrl-X).
ESC SUB   GIN mode (ESC  Ctrl-Z).
ESC FS    Special Point Plot Mode (ESC  Ctrl-\).
ESC 8     Select Large Character Set.
ESC 9     Select #2 Character Set.
ESC :     Select #3 Character Set.
ESC ;     Select Small Character Set.


OSC Ps ; Pt BEL
          Set Text Parameters of VT window.
            Ps = 0  ⇒  Change Icon Name and Window Title to Pt.
            Ps = 1  ⇒  Change Icon Name to Pt.
            Ps = 2  ⇒  Change Window Title to Pt.
            Ps = 4 6  ⇒  Change Log File to Pt.  This is normally 
                         disabled by a compile-time option.

Window and Icon Titles
    Some scripts use echo with options -e and -n to tell the shell to
    interpret the string “\e” as the escape character and to suppress a
    trailing newline on output.  Those are not portable, nor recommended.
    Instead, use printf (POSIX).

    For example, to set the window title to “Hello world!”, you could use
    one of these commands in a script:

        printf '\033]2;Hello world!\033\\'
        printf '\033]2;Hello world!\007'
        printf '\033]2;%s\033\\' "Hello world!"
        printf '\033]2;%s\007' "Hello world!"

    The printf command interprets the octal value “\033” for escape, and
    (since it was not given in the format) omits a trailing newline from
    the output.

    Some programs (such as screen(1)) set both window- and icon-titles at
    the same time, using a slightly different control sequence:

        printf '\033]0;Hello world!\033\\'
        printf '\033]0;Hello world!\007'
        printf '\033]0;%s\033\\' "Hello world!"
        printf '\033]0;%s\007' "Hello world!"

    The difference is the parameter “0” in each command.  Most window
    managers will honor either window title or icon title.  Some will make
    a distinction and allow you to set just the icon title.  You can tell
    xterm to ask for this with a different parameter in the control
    sequence:

        printf '\033]1;Hello world!\033\\'
        printf '\033]1;Hello world!\007'
        printf '\033]1;%s\033\\' "Hello world!"
        printf '\033]1;%s\007' "Hello world!"

\033]

2

;

My Window Title

\007

$ printf '\033]2;My Window Title\007'

printf "Here is a %sbold red%s word\n" "$(tput bold)""$(tput setf 4)" "$(tput sgr0)"

$ printf "Here is a \033[0;1mbold %sred %sword \n" `tput bold` `tput AF 1` `tput me`
Here is a bold red word 

$ printf "Here is a \033[;1mbold %sred %sword \n" `tput bold` `tput AF 1` `tput me`
Here is a bold red word 

$ printf "Here is a %s\033[0;1mbold %sred %sword\n" `tput bold` `tput me` `tput AF 1` `tput me`
Here is a bold red word

$ printf "Here is %sa %s\033[0;1mbold %sred %sword\n" `tput md ` `tput me` `tput AF 1` `tput me`

% printf "Here is %sa %s\033[;1mbold %sred %sword\n" `tput md ` `tput me` `tput AF 1` `tput me`
Here is a bold red word

$ printf "Here is a %s\033[;1mbold %sred %sword\n" `tput md ` `tput AF 1` `tput me`
Here is a bold red word

---- snip ----

Predefined Capabilities
     The following is a complete table of the capabilities included in a
     terminfo description block and available to terminfo-using code.
     In each line of the table,
  
     The variable is the name by which the programmer (at the terminfo
     level) accesses the capability.

     The capname is the short name used in the text of the database, and is
     used by a person updating the database.  Whenever possible, capnames
     are chosen to be the same as or similar to the ANSI X3.64-1979 standard
     (now superseded by ECMA-48, which uses identical or very similar
     names).  Semantics are also intended to match those of the
     specification.

     The termcap code is the old termcap capability name (some capabilities
     are new, and have names which termcap did not originate).
  
     Capability names have no hard length limit, but an informal limit of 5
     characters has been adopted to keep them short and to allow the tabs in
     the source file Caps to line up nicely.

---- snip ----

These are the string capabilities:

   Variable                   Cap-      TCap   Description
    String                    name      Code

---- snip ----

   set_a_foreground           setaf     AF     Set foreground
                                               color to #1, using
                                               ANSI escape

---- snip ----

   exit_attribute_mode        sgr0      me     turn off all
                                               attributes

---- snip ----

     Most color terminals are either “Tektronix-like” or “HP-like”:
  
     *   Tektronix-like terminals have a predefined set of N colors (where N
         is usually 8), and can set character-cell foreground and background
         characters independently, mixing them into N * N color-pairs.
  
     *   On HP-like terminals, the user must set each color pair up
         separately (foreground and background are not independently
         settable).  Up to M color-pairs may be set up from 2*M different
         colors.  ANSI-compatible terminals are Tektronix-like.
  
     Some basic color capabilities are independent of the color method.  The
     numeric capabilities colors and pairs specify the maximum numbers of
     colors and color-pairs that can be displayed simultaneously.  The op
     (original pair) string resets foreground and background colors to their
     default values for the terminal.  The oc string resets all colors or
     color-pairs to their default values for the terminal.  Some terminals
     (including many PC terminal emulators) erase screen areas with the
     current background color rather than the power-up default background;
     these should have the boolean capability bce.

     While the curses library works with color pairs (reflecting the
     inability of some devices to set foreground and background colors
     independently), there are separate capabilities for setting these
     features:
  
     *   To change the current foreground or background color on a
         Tektronix-type terminal, use setaf (set ANSI foreground) and setab
         (set ANSI background) or setf (set foreground) and setb (set
         background).  These take one parameter, the color number.

         The SVr4 documentation describes only setaf/setab; the XPG4 draft
         says that "If the terminal supports ANSI escape sequences to set
         background and foreground, they should be coded as setaf and setab,
         respectively.

     *   If the terminal supports other escape sequences to set background
         and foreground, they should be coded as setf and setb,
         respectively.  The vidputs and the refresh(3X) functions use the
         setaf and setab capabilities if they are defined.
  
     The setaf/setab and setf/setb capabilities take a single numeric
     argument each.  Argument values 0-7 of setaf/setab are portably defined
     as follows (the middle column is the symbolic #define available in the
     header for the curses or ncurses libraries).  The terminal hardware is
     free to map these as it likes, but the RGB values indicate normal
     locations in color space.
  
                  Color       #define       Value       RGB
                  black     COLOR_BLACK       0     0, 0, 0
                  red       COLOR_RED         1     max,0,0
                  green     COLOR_GREEN       2     0,max,0
                  yellow    COLOR_YELLOW      3     max,max,0
                  blue      COLOR_BLUE        4     0,0,max
                  magenta   COLOR_MAGENTA     5     max,0,max
                  cyan      COLOR_CYAN        6     0,max,max
                  white     COLOR_WHITE       7     max,max,max


---- snip ----

Highlighting, Underlining, and Visible Bells
     If your terminal has one or more kinds of display attributes, these can
     be represented in a number of different ways.  You should choose one
     display form as standout mode, representing a good, high contrast,
     easy-on-the-eyes, format for highlighting error messages and other
     attention getters.  (If you have a choice, reverse video plus half-
     bright is good, or reverse video alone.)  The sequences to enter and
     exit standout mode are given as smso and rmso, respectively.  If the
     code to change into or out of standout mode leaves one or even two
     blank spaces on the screen, as the TVI 912 and Teleray 1061 do, then
     xmc should be given to tell how many spaces are left.
  
     Codes to begin underlining and end underlining can be given as smul and
     rmul respectively.  If the terminal has a code to underline the current
     character and move the cursor one space to the right, such as the
     Microterm Mime, this can be given as uc.

     Other capabilities to enter various highlighting modes include blink
     (blinking) bold (bold or extra bright) dim (dim or half-bright) invis
     (blanking or invisible text) prot (protected) rev (reverse video) sgr0
     (turn off all attribute modes) smacs (enter alternate character set
     mode) and rmacs (exit alternate character set mode).  Turning on any of
     these modes singly may or may not turn off other modes.
  
     If there is a sequence to set arbitrary combinations of modes, this
     should be given as sgr (set attributes), taking 9 parameters.  Each
     parameter is either 0 or nonzero, as the corresponding attribute is on
     or off.  The 9 parameters are, in order: standout, underline, reverse,
     blink, dim, bold, blank, protect, alternate character set.  Not all
     modes need be supported by sgr, only those for which corresponding
     separate attribute commands exist.
  
     For example, the DEC vt220 supports most of the modes:
  
             tparm parameter      attribute        escape sequence
  
             none                 none             \E[0m
             p1                   standout         \E[0;1;7m
             p2                   underline        \E[0;4m
             p3                   reverse          \E[0;7m
             p4                   blink            \E[0;5m
             p5                   dim              not available
             p6                   bold             \E[0;1m
             p7                   invis            \E[0;8m
             p8                   protect          not used
             p9                   altcharset       ^O (off) ^N (on)

     We begin each escape sequence by turning off any existing modes, since
     there is no quick way to determine whether they are active.  Standout
     is set up to be the combination of reverse and bold.  The vt220
     terminal has a protect mode, though it is not commonly used in sgr
     because it protects characters on the screen from the host's erasures.
     The altcharset mode also is different in that it is either ^O or ^N,
     depending on whether it is off or on.  If all modes are turned on, the
     resulting sequence is \E[0;1;4;5;7;8m^N.

  
---- snip ----

$ man Term::ANSIColor

$ infocmp -1x | grep E3

    E3=\E[3J,

https://invisible-island.net/ncurses/

######## TERMINAL TYPE DESCRIPTIONS SOURCE FILE
#
# This version of terminfo.src is distributed with ncurses and is maintained
# by Thomas E. Dickey (TD).
---- snip ----

$ printf %d\\n 061
49

Convert octal to hexadecimal:
$ printf %x\\n 061
31

$ printf '\033[1;34m%-6s\033[m' "This is blue text"
This is blue text$ 

$ printf '\033[1;33m%-6s\033[m' "This is yellow text"
This is yellow text$ 
 
$ printf '\033[1;31m%-6s\033[m' "This is red text"
This is red text$ 

       Character escape sequences are in backslash notation as defined in the
       ANSI X3.159-1989 (“ANSI C89”), with extensions.  The characters and their
       meanings are as follows:
  
             \a      Write a <bell> character.
             \b      Write a <backspace> character.
             \c      Ignore remaining characters in this string.
             \f      Write a <form-feed> character.
             \n      Write a <new-line> character.
             \r      Write a <carriage return> character.
             \t      Write a <tab> character.
             \v      Write a <vertical tab> character.
             \´      Write a <single quote> character.
             \\      Write a backslash character.
             \num    Write a byte whose value is the 1-, 2-, or 3-digit octal
                     number num.  Multibyte characters can be constructed using
                     multiple \num sequences.
  
       Each format specification is introduced by the percent character (``%'').
       The remainder of the format specification includes, in the following
       order:

$ printf %o\\n 65
101
 
$ printf '\101'
A$ 

$ printf '\101 \102 \103 \n'
A B C 


$ printf '\033[9mTest\n\033[\060m' | od -c
0000000  033   [   9   m   T   e   s   t  \n 033   [   0   m            
0000015

$ printf '\033[9mCrossed-out characters.\n\033[\060m'

$ printf '\033[1mBold. VT100\n\033[\060m'
 
$ printf '\033[2mFaint\n\033[\060m'
    
$ printf '\033[3mItalicized\n\033[\060m'

$ printf '\033[4mUnderlined. VT100\n\033[\060m'
 
$ printf '\033[5mBlink. VT100\n\033[\060m'

$ printf '\033[7mInverse\n\033[\060m'

$ printf '\033[8mInvisible (hidden)\n\033[\060m'
                  
$ printf '\033[9mCrossed-out characters.\n\033[\060m'
 
$ printf '\033[21mDoubly-underlined.\n\033[\060m'


$ printf '\033[31mRed foreground.\n\033[\060m'
Red foreground.
 
$ printf '\033[32mGreen foreground.\n\033[\060m'
Green foreground.
 
$ printf '\033[33mYellow foreground.\n\033[\060m'
Yellow foreground.
 
$ printf '\033[34mBlue foreground.\n\033[\060m'
Blue foreground.
 
$ printf '\033[35mMagenta foreground.\n\033[\060m'
Magenta foreground.

$ ps $$
  PID TT  STAT    TIME COMMAND
95398  5  Ss   0:01.19 -tcsh (tcsh)

$ printf %s\\n "$SHELL"
/bin/tcsh

$ printf %s\\n "$TERM"
xterm-new
 
$ echo -e \\e[S
-e \e[S

$ set | grep echo
echo_style      bsd
 
$ set echo_style = both

$ set | grep echo
echo_style      both
 
$ echo -e \\e[S
-e 

$ echo \\e[S

$ echo \\e[H\e[2J

$ printf '\033[H\033[2J'

7-Bit ASCII Code

---- snip ----

Control Characters 
---- snip ----
Char  Octal  Binary
ESC     033  0011011
---- snip ----

Control Characters

+--------+-----------+-------+-------------------------------------+
| Name   | Character | Octal | Function                            |
|        | Mnemonic  | Code  |                                     |
| ---- snip ----     |       |                                     |
+--------------------+-------+-------------------------------------+
| Escape | ESC       | 033   | Processed as a sequence introducer. |
| ---- snip ----     |       |                                     |
+--------+-----------+-------+-------------------------------------+

Programmer Information
======================

Standard Character Set
----------------------

C0 Control Characters 
---------------------

+--------+----------+-------+-------------------------------------+
| Name   | Mnemonic | Octal | Function                            |
|        |          | Code  |                                     |
| ---- snip ----    |       |                                     |
+-------------------+-------+-------------------------------------+
| Escape | ESC      | 033   | Introduces an escape sequence.      |
|        |          |       | When executed in graphics mode      |
|        |          |       | causes the terminal to exit and     |
|        |          |       | start processing the sequence.      |
| ---- snip ----    |       |                                     |
+--------+----------+-------+-------------------------------------+

Graphics    Mode C0   Control Characters
----------------------------------------

+------------+----------+-------+---------------------------------------------+
| Name       | Mnemonic | Octal | Function                                    |
|            |          | Code  |                                             |
+------------+----------+-------+---------------------------------------------+
| Cancel     | CAN      | 030   |Immediately causes an exit from graphics mode|
+------------+----------+-------+---------------------------------------------+
| Substitute | SUB      | 032   |SUB is processed as a one column space       |
+------------+----------+-------+---------------------------------------------+
| Escape     | ESC      | 033   |Causes the terminal to exit graphics mode and|
|            |          |       |start processing the sequence                |
+------------+----------+-------+---------------------------------------------+

---- snip ----

Escape and Control Sequences
-----------------------------

Note: V2 microcode supports the use of 8-bit characters to replace certain 7-bit sequences.

8-Bit Character [*] Equivalents for 7-Bit Escape Sequences 
----------------------------------------------------------


+-----------------+---------------+-----------------------------+
| 7-Bit           | 8-Bit         | Function                    |
| Sequence        | Character [*] |                             |
|                 |               |                             | 
|  Octal          |       Octal   |                             |
+-----------------+---------------+-----------------------------+
|                 |               |                             |
| ---- snip ----  |               |                             |
|                 |               |                             |
| ESC [  033 133  =  CSI  233     | Control sequence introducer |
|                 |               |                             | 
| ---- snip ----  |               |                             |
+-----------------+---------------+-----------------------------+

[*] V.2. only

sequence-lead-in (arrow prefix, meta prefix, ^X)
        Indicates that the following characters are part of a multi-key
        sequence.  Binding a command to a multi-key sequence really
        creates two bindings: the first character to sequence-lead-in
        and the whole sequence to the command.  All sequences beginning
        with a character bound to sequence-lead-in are effectively
        bound to undefined-key unless bound to another command.

  \a      Bell
  \b      Backspace
  \e      Escape
  \f      Form feed
  \n      Newline
  \r      Carriage return
  \t      Horizontal tab
  \v      Vertical tab
  \nnn    The ASCII character corresponding to the octal
          number nnn

  `\' nullifies the special meaning of the following character,
  if it has any, notably `\' and `^'.

---- snip ----
REFERENCE
       The next sections of this manual describe all of the available Builtin
       commands, Special aliases and Special shell variables.

   Builtin commands

---- snip ----
       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
               Without options, the first form lists all bound keys and the
               editor command to which each is bound, the second form lists
               the editor command to which key is bound and the third form
               binds the editor command command to key.  Options include:
---- snip ----
             -b  key is interpreted as a control character written
                   ^character (e.g., `^A') or C-character (e.g., `C-A'), a
                   meta character written M-character (e.g., `M-A'), a
                   function key written F-string (e.g., `F-string'), or an
                   extended prefix key written X-character (e.g., `X-A').

$ man ascii

ASCII(7)           FreeBSD Miscellaneous Information Manual           ASCII(7)

NAME
     ascii – octal, hexadecimal, decimal and binary ASCII character sets

DESCRIPTION
     The octal set:

     000 NUL  001 SOH  002 STX  003 ETX  004 EOT  005 ENQ  006 ACK  007 BEL
     010 BS   011 HT   012 LF   013 VT   014 FF   015 CR   016 SO   017 SI
     020 DLE  021 DC1  022 DC2  023 DC3  024 DC4  025 NAK  026 SYN  027 ETB
     030 CAN  031 EM   032 SUB  033 ESC  034 FS   035 GS   036 RS   037 US
     040 SP   041  !   042  "   043  #   044  $   045  %   046  &   047  '
     050  (   051  )   052  *   053  +   054  ,   055  -   056  .   057  /
     060  0   061  1   062  2   063  3   064  4   065  5   066  6   067  7
     070  8   071  9   072  :   073  ;   074  <   075  =   076  >   077  ?
     100  @   101  A   102  B   103  C   104  D   105  E   106  F   107  G
     110  H   111  I   112  J   113  K   114  L   115  M   116  N   117  O
     120  P   121  Q   122  R   123  S   124  T   125  U   126  V   127  W
     130  X   131  Y   132  Z   133  [   134  \   135  ]   136  ^   137  _
     140  `   141  a   142  b   143  c   144  d   145  e   146  f   147  g
     150  h   151  i   152  j   153  k   154  l   155  m   156  n   157  o
     160  p   161  q   162  r   163  s   164  t   165  u   166  v   167  w

---- snip ----

---- snip ----
The following special characters are extensions defined by this system
and are not a part of IEEE Std 1003.1 (“POSIX.1”) termios.

---- snip ----

  LNEXT   Special character on input and is recognized if the IEXTEN flag
          is set.  Receipt of this character causes the next character to
          be taken literally.

---- snip ----

Local Modes
  Values of the c_lflag field describe the control of various functions,
  and are composed of the following masks.

        ECHOKE      /* visual erase for line kill */
        ECHOE       /* visually erase chars */
        ECHO        /* enable echoing */
        ECHONL      /* echo NL even if ECHO is off */
        ECHOPRT     /* visual erase mode for hardcopy */
        ECHOCTL     /* echo control chars as ^(Char) */

---- snip ----

  If ECHOCTL is set, the system echoes control characters in a visible
  fashion using a **caret** followed by the **control character**.

---- snip ----

Special Control Characters
  The special control characters values are defined by the array c_cc.
  This table lists the array index, the corresponding special character,
  and the system default value.  For an accurate list of the system
  defaults, consult the header file <sys/ttydefaults.h>.

        Index Name    Special Character    Default Value
        VEOF          EOF                  ^D
        VEOL          EOL                  _POSIX_VDISABLE
        VEOL2         EOL2                 _POSIX_VDISABLE
        VERASE        ERASE                ^? ‘\177’
        VWERASE       WERASE               ^W
        VKILL         KILL                 ^U
        VREPRINT      REPRINT              ^R
        VINTR         INTR                 ^C
        VQUIT         QUIT                 ^\\ ‘\34’
        VSUSP         SUSP                 ^Z
        VDSUSP        DSUSP                ^Y
        VSTART        START                ^Q
        VSTOP         STOP                 ^S
        VLNEXT        LNEXT                ^V
        VDISCARD      DISCARD              ^O
        VMIN          ---                  1
        VTIME         ---                  0
        VSTATUS       STATUS               ^T

---- snip ----

  The initial values of the flags and control characters after open() is
  set according to the values in the header <sys/ttydefaults.h>.

SEE ALSO
     stty(1), tcgetsid(3), tcgetwinsize(3), tcsendbreak(3), tcsetattr(3),
     tcsetsid(3), tty(4), stack(9)

$ wc -l /usr/include/sys/ttydefaults.h
     112 /usr/include/sys/ttydefaults.h

$ cat /usr/include/sys/ttydefaults.h
/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
---- snip ----
 *
 *      @(#)ttydefaults.h       8.4 (Berkeley) 1/21/94
 */

/*
 * System wide defaults for terminal state.
 */
#ifndef _SYS_TTYDEFAULTS_H_
#define _SYS_TTYDEFAULTS_H_

/*
 * Defaults on "first" open.
 */
#define TTYDEF_IFLAG    (BRKINT | ICRNL | IMAXBEL | IXON | IXANY)
#define TTYDEF_OFLAG    (OPOST | ONLCR)
#define TTYDEF_LFLAG_NOECHO (ICANON | ISIG | IEXTEN)
#define TTYDEF_LFLAG_ECHO (TTYDEF_LFLAG_NOECHO \
        | ECHO | ECHOE | ECHOKE | ECHOCTL)
#define TTYDEF_LFLAG TTYDEF_LFLAG_ECHO
#define TTYDEF_CFLAG    (CREAD | CS8 | HUPCL)
#define TTYDEF_SPEED    (B9600)

/*
 * Control Character Defaults
 */
/*
 * XXX: A lot of code uses lowercase characters, but control-character
 * conversion is actually only valid when applied to uppercase
 * characters. We just treat lowercase characters as if they were
 * inserted as uppercase.
 */
#define CTRL(x) ((x) >= 'a' && (x) <= 'z' ? \
        ((x) - 'a' + 1) : (((x) - 'A' + 1) & 0x7f))
#define CEOF            CTRL('D')
#define CEOL            0xff            /* XXX avoid _POSIX_VDISABLE */
#define CERASE          CTRL('?')
#define CERASE2         CTRL('H')
#define CINTR           CTRL('C')
#define CSTATUS         CTRL('T')
#define CKILL           CTRL('U')
#define CMIN            1
#define CQUIT           CTRL('\\')
#define CSUSP           CTRL('Z')
#define CTIME           0
#define CDSUSP          CTRL('Y')
#define CSTART          CTRL('Q')
#define CSTOP           CTRL('S')
#define CLNEXT          CTRL('V')
#define CDISCARD        CTRL('O')
#define CWERASE         CTRL('W')
#define CREPRINT        CTRL('R')
#define CEOT            CEOF
/* compat */
#define CBRK            CEOL
#define CRPRNT          CREPRINT
#define CFLUSH          CDISCARD

/* PROTECTED INCLUSION ENDS HERE */
#endif /* !_SYS_TTYDEFAULTS_H_ */

/*
 * #define TTYDEFCHARS to include an array of default control characters.
 */
#ifdef TTYDEFCHARS

#include <sys/cdefs.h>
#include <sys/_termios.h>

static const cc_t ttydefchars[] = {
        CEOF, CEOL, CEOL, CERASE, CWERASE, CKILL, CREPRINT, CERASE2, CINTR,
        CQUIT, CSUSP, CDSUSP, CSTART, CSTOP, CLNEXT, CDISCARD, CMIN, CTIME,
        CSTATUS, _POSIX_VDISABLE
};
_Static_assert(sizeof(ttydefchars) / sizeof(cc_t) == NCCS,
    "Size of ttydefchars does not match NCCS");

#undef TTYDEFCHARS
#endif /* TTYDEFCHARS */

$ grep CTRL /usr/include/sys/ttydefaults.h | grep V
#define CLNEXT          CTRL('V')

Dec Hex    Dec Hex    Dec Hex  Dec Hex  Dec Hex  Dec Hex   Dec Hex   Dec Hex
  0 00 NUL  16 10 DLE  32 20    48 30 0  64 40 @  80 50 P   96 60 `  112 70 p
  1 01 SOH  17 11 DC1  33 21 !  49 31 1  65 41 A  81 51 Q   97 61 a  113 71 q
  2 02 STX  18 12 DC2  34 22 "  50 32 2  66 42 B  82 52 R   98 62 b  114 72 r
  3 03 ETX  19 13 DC3  35 23 #  51 33 3  67 43 C  83 53 S   99 63 c  115 73 s
  4 04 EOT  20 14 DC4  36 24 $  52 34 4  68 44 D  84 54 T  100 64 d  116 74 t
  5 05 ENQ  21 15 NAK  37 25 %  53 35 5  69 45 E  85 55 U  101 65 e  117 75 u
  6 06 ACK  22 16 SYN  38 26 &  54 36 6  70 46 F  86 56 V  102 66 f  118 76 v
  7 07 BEL  23 17 ETB  39 27 '  55 37 7  71 47 G  87 57 W  103 67 g  119 77 w
  8 08 BS   24 18 CAN  40 28 (  56 38 8  72 48 H  88 58 X  104 68 h  120 78 x
  9 09 HT   25 19 EM   41 29 )  57 39 9  73 49 I  89 59 Y  105 69 i  121 79 y
 10 0A LF   26 1A SUB  42 2A *  58 3A :  74 4A J  90 5A Z  106 6A j  122 7A z
 11 0B VT   27 1B ESC  43 2B +  59 3B ;  75 4B K  91 5B [  107 6B k  123 7B {
 12 0C FF   28 1C FS   44 2C ,  60 3C <  76 4C L  92 5C \  108 6C l  124 7C |
 13 0D CR   29 1D GS   45 2D -  61 3D =  77 4D M  93 5D ]  109 6D m  125 7D }
 14 0E SO   30 1E RS   46 2E .  62 3E >  78 4E N  94 5E ^  110 6E n  126 7E ~
 15 0F SI   31 1F US   47 2F /  63 3F ?  79 4F O  95 5F _  111 6F o  127 7F DEL

   0000000 NUL    0100000      1000000 @    1100000 `
   0000001 SOH    0100001 !    1000001 A    1100001 a
   0000010 STX    0100010 "    1000010 B    1100010 b
   0000011 ETX    0100011 #    1000011 C    1100011 c
   0000100 EOT    0100100 $    1000100 D    1100100 d
   0000101 ENQ    0100101 %    1000101 E    1100101 e
   0000110 ACK    0100110 &    1000110 F    1100110 f
   0000111 BEL    0100111 '    1000111 G    1100111 g
   0001000 BS     0101000 (    1001000 H    1101000 h
   0001001 HT     0101001 )    1001001 I    1101001 i
   0001010 LF     0101010 *    1001010 J    1101010 j
   0001011 VT     0101011 +    1001011 K    1101011 k
   0001100 FF     0101100 ,    1001100 L    1101100 l
   0001101 CR     0101101 -    1001101 M    1101101 m
   0001110 SO     0101110 .    1001110 N    1101110 n
   0001111 SI     0101111 /    1001111 O    1101111 o
   0010000 DLE    0110000 0    1010000 P    1110000 p
   0010001 DC1    0110001 1    1010001 Q    1110001 q
   0010010 DC2    0110010 2    1010010 R    1110010 r
   0010011 DC3    0110011 3    1010011 S    1110011 s
   0010100 DC4    0110100 4    1010100 T    1110100 t
   0010101 NAK    0110101 5    1010101 U    1110101 u
   0010110 SYN    0110110 6    1010110 V    1110110 v
   0010111 ETB    0110111 7    1010111 W    1110111 w
   0011000 CAN    0111000 8    1011000 X    1111000 x
   0011001 EM     0111001 9    1011001 Y    1111001 y
   0011010 SUB    0111010 :    1011010 Z    1111010 z
   0011011 ESC    0111011 ;    1011011 [    1111011 {
   0011100 FS     0111100 <    1011100 \    1111100 |
   0011101 GS     0111101 =    1011101 ]    1111101 }
   0011110 RS     0111110 >    1011110 ^    1111110 ~
   0011111 US     0111111 ?    1011111 _    1111111 DEL

% printf "%03o\n" 27
033

LESSKEY(1)                  General Commands Manual                 LESSKEY(1)
  
NAME
       lesskey - customize key bindings for less
  
SYNOPSIS (deprecated)
       lesskey [-o output] [--] [input]
       lesskey [--output=output] [--] [input]
       lesskey -V
       lesskey --version

---- snip ----

DESCRIPTION
       A lesskey file specifies a set of key bindings and environment
       variables to be used by subsequent invocations of less.
  
FILE FORMAT
       The input file consists of one or more sections.  Each section starts
       with a line that identifies the type of section.
       Possible sections are:
  
         #command
                Customizes command key bindings.

---- snip ----

COMMAND SECTION
       The command section begins with the line
  
       #command
  
       If the command section is the first section in the file, this line may
       be omitted.  The command section consists of lines of the form:
  
            string <whitespace> action [extra-string] <newline>

---- snip ----

       The characters in the string may appear literally, or be prefixed by
       a caret to indicate a control key.  A backslash followed by one to
       three octal digits may be used to specify a character by its octal
       value.  A backslash followed by certain characters specifies input
       characters as follows:

           \b   BACKSPACE   (0x08)
           \e   ESCAPE      (0x1B)
           \n   NEWLINE     (0x0A)
           \r   RETURN      (0x0D)
           \t   TAB         (0x09)

---- snip ----

COMMANDS
         In the following descriptions, ^X means control-X.  ESC stands for the
         ESCAPE key; for example ESC-v means the two character sequence
         "ESCAPE", then "v".

---- snip ----

  LINE EDITING
         When entering command line at the bottom of the screen (for example, a
         filename for the :e command, or the pattern for a search command),
         certain keys can be used to manipulate the command line.  Most commands
         have an alternate form in [ brackets ] which can be used if a key does
         not exist on a particular keyboard.  (Note that the forms beginning
         with ESC do not work in some MS-DOS and Windows systems because ESC is
         the line erase character.)  Any of these special keys may be entered
         literally by preceding it with the "literal" character, either ^V or
         ^A.  A backslash itself may also be entered literally by entering two
         backslashes.

         Note that some keys may be the same as commonly used control keys,
         e.g., KEY_ENTER versus control/M, KEY_BACKSPACE versus control/H.  Some
         curses implementations may differ according to whether they treat these
         control keys specially (and ignore the terminfo), or use the terminfo
         definitions.  Ncurses uses the terminfo definition.  If it says that
         KEY_ENTER is control/M, getch will return KEY_ENTER when you press
         control/M.

The stty utility sets certain terminal I/O options for the device that
is the current standard input. Without arguments, stty reports the set-
tings of certain options.

In this report, if a character is preceded by a caret (^), then the
value of that option is the corresponding control character (for exam-
ple,  ^h is <CTRL-h>.  In this case, recall that <CTRL-h> is the same as
the <BACKSPACE> key).  The sequence ^@ means that an option has a null
value.

---- snip ----

Control Assignments
    control-character  c     Set control-character to c, where:

                             control-character

                                 is ctab, discard, dsusp, eof, eol, eol2,
                                 erase, intr, kill,  lnext,  quit, reprint,
                                 start, stop, susp, swtch, or werase  (ctab
                                 is used with -stappl, see termio(7I)).
                                 For information on swtch, see NOTES.

    c

    If c is a single character, the control
    character is set to that character.

    In the POSIX locale, if c is preceded by a
    caret (^) indicating an escape from the
    shell and is one of those listed in the ^c
    column of the following table, then its
    value used (in the  Value  column) is the
    corresponding control character (for exam-
    ple, ``^d''  is a <CTRL-d>). ``^?'' is in-
    terpreted as <DEL>  and  ``^-''  is inter-
    preted as undefined.

    +------------------+-------------------+------------------+
    |  ^c      Value   |  ^c      Value    |  ^c      Value   |
    | a, A     <SOH>   | l, L     <FF>     | w, W     <ETB>   |
    | b, B     <STX>   | m, M     <CR>     | x, X     <CAN>   |
    | c, C     <ETX>   | n, N     <SO>     | y, Y     <EM>    |
    | d, D     <EOT>   | o, O     <SI>     | z, Z     <SUB>   |
    | e, E     <ENQ>   | p, P     <DLE>    | [        <ESC>   |
    | f, F     <ACK>   | q, Q     <DC1>    | \        <FS>    |
    | g, G     <BEL>   | r, R     <DC2>    | ]        <GS>    |
    | h, H     <BS>    | s, S     <DC3>    | ^        <RS>    |
    | i, I     <HT>    | t, T     <DC4>    | _        <US>    |
    | j, J     <LF>    | u, U     <NAK>    | ?        <DEL>   |
    | k, K     <VT>    | v, V     <SYN>    |                  |
    +------------------+-------------------+------------------+

---- snip ----
Special Characters
    Certain characters have special functions on input.  These functions and
    their default character values are summarized as follows:

---- snip ----

       LNEXT         (Control-v  or ASCII SYN) causes the special meaning of
                     the next character to be ignored.  This works for all
                     the special characters mentioned above.  It allows char-
                     acters to be input that would otherwise be interpreted
                     by the system (for example KILL, QUIT).  The character
                     values for INTR, QUIT, ERASE, WERASE, KILL, REPRINT,
                     EOF, EOL, EOL2, SWTCH, SUSP, DSUSP, STOP, START, DIS-
                     CARD, and LNEXT may be changed to suit individual
                     tastes.  If the value of a special control character is
                     _POSIX_VDISABLE (0), the function of that special con-
                     trol character is disabled.  The ERASE, KILL, and EOF
                     characters may be escaped by a preceding backslash  (\)
                     character, in which case no special function is done.
                     Any of the special characters may be preceded by the
                     LNEXT  character, in which case no special function is
                     done.

---- snip ----

Terminal Parameters
    The parameters that control the behavior of devices and modules provid-
    ing the termios interface are specified by the termios structure de-
    fined by  termios.h.  Several  ioctl(2)  system calls that fetch or
    change these parameters use this structure that contains the following
    members:

           tcflag_t c_iflag;  /* input modes */
           tcflag_t  c_oflag; /* output modes */
           tcflag_t  c_cflag; /* control modes */
           tcflag_t  c_lflag; /* local modes */
           cc_t  c_cc[NCCS];  /* control chars */

    The special control characters are defined by the array c_cc.  The sym-
    bolic name NCCS is the size of the Control-character array and is also
    defined by  <termios.h>.  The relative positions, subscript names, and
    typical default values for each function are as follows:

    +--------------------+--------------------+-----------------------+
    | Relative Position  | Subscript Name     | Typical Default Value |
    +--------------------+--------------------+-----------------------+
    | 0                  | VINTR              | ETX                   |
    +--------------------+--------------------+-----------------------+
    | 1                  | VQUIT              | FS                    |
    +--------------------+--------------------+-----------------------+
    | 2                  | VERASE             | DEL                   |
    +--------------------+--------------------+-----------------------+
    | 3                  | VKILL              | NAK                   |
    +--------------------+--------------------+-----------------------+
    | 4                  | VEOF               | EOT                   |
    +--------------------+--------------------+-----------------------+
    | 5                  | VEOL               | NUL                   |
    +--------------------+--------------------+-----------------------+
    | 6                  | VEOL2              | NUL                   |
    +--------------------+--------------------+-----------------------+
    | 7                  | VWSTCH             | NUL                   |
    +--------------------+--------------------+-----------------------+
    | 8                  | VSTART             | NUL                   |
    +--------------------+--------------------+-----------------------+
    | 9                  | VSTOP              | DC3                   |
    +--------------------+--------------------+-----------------------+
    | 10                 | VSUSP              | SUB                   |
    +--------------------+--------------------+-----------------------+
    | 11                 | VDSUSP             | EM                    |
    +--------------------+--------------------+-----------------------+
    | 12                 | VREPRINT           | DC2                   |
    +--------------------+--------------------+-----------------------+
    | 13                 | VDISCARD           | SI                    |
    +--------------------+--------------------+-----------------------+
    | 14                 | VWERASE            | ETB                   |
    +--------------------+--------------------+-----------------------+
    | 15                 | VLNEXT             | SYN                   |
    +--------------------+--------------------+-----------------------+
    | 16-19              | Reserved           |                       |
    +--------------------+--------------------+-----------------------+

---- snip ----

Local Modes
    The c_lflag field contains the following single bit flags that
    control various functions:

    ECHO   Enable echoing of input characters.  Most input characters are
           echoed as they are.  Control characters are echoed as ^X where X is
           the letter used to say that the control character is CTRL-X.
           The CR, NL and TAB characters are echoed with their normal effect
           unless they are escaped by  LNEXT.
---- snip ----

Dec  Hex  Char       Description                                 Octal  Pos  *)
---- snip ---- 
22   $16  SYN (^V)   Synchronous Idle                            026    1/6  SY
                     TC9 Transmission control character 9  

                     Used as "time-fill" in synchronous transmission.
                     Sent during an idle condition to retain a signal when
                     there are no other characters to send. 

                     Note: SYN has been used by synchronous modems, which
                     have to send data constantly. — Beginning each
                     transmission with at least two SYN characters is a way
                     to achieve synchronization.  The receiving station will
                     possibly ignore SYN, since it doesn't belong to the actual
                     data content.
---- snip ---- 

---- snip ----
  VI TEXT INPUT COMMANDS
---- snip ----
       ⟨literal next⟩
               Escape the next character from any special meaning.  
               The ⟨literal next⟩ character is usually ⟨control-V⟩.
---- snip ----

NOTATION
       An Emacs-style notation is used to denote keystrokes.  Control keys are
       denoted by C-key, e.g., C-n means Control-N.  Similarly, meta keys are
       denoted by M-key, so M-x means Meta-X.  (On keyboards without a meta
       key, M-x means ESC x, i.e., press the Escape key then the x key.  This
       makes ESC the meta prefix.  The combination M-C-x means ESC-Control-x,
       or press the Escape key then hold the Control key while pressing the x
       key.)


     VI Mode bindings
  
               VI Insert Mode functions
  
               "C-D"  vi-eof-maybe
               "C-H"  backward-delete-char
               "C-I"  complete
               "C-J"  accept-line
               "C-M"  accept-line
               "C-R"  reverse-search-history
               "C-S"  forward-search-history
               "C-T"  transpose-chars
               "C-U"  unix-line-discard
               "C-V"  quoted-insert

               ---- snip ----

---- snip ----
    Miscellaneous Commands
    ----------------------
Shortcut:     CTRL-v     
Description:  Insert a character literally (quoted insert)
---- snip ----

    Examples and Tips
    -----------------
* Use CTRL-v to insert character literally, for example, CTRL-v CTRL-r would
  insert CTRL-r in the command line.
* See man bash, man readline, and builtin bind command for modifying the
  default behavior.

---- snip ----
    Commands for Changing Text
    --------------------------
---- snip ----
Shortcut:       C-q or C-v    
Function Name:  quoted-insert 
Description:    Quoted insert
---- snip ----

$ man -k editline
editline, el_deletestr, el_end, el_get, el_getc, el_gets, el_init, el_init_fd, el_insertstr, el_line, el_parse, el_push, el_reset, el_resize, el_set, el_source, el_wdeletestr, el_wget, el_wgetc, el_wgets, el_winsertstr, el_wline, el_wparse, el_wpush, el_wset, history_end, history_init, history_w, history_wend, history_winit, tok_end, tok_init, tok_line, tok_reset, tok_str, tok_wend, tok_winit, tok_wline, tok_wreset, tok_wstr, el_history, el_cursor, history(3) - line editor, history and tokenization functions
editrc(5) - configuration file for editline library
editline(7) - line editing user interface

$ man 3 editline
$ man 7 editline

$ man -a -w terminfo
/usr/share/man/man5/terminfo.5.gz
/usr/local/man/man5/terminfo.5.gz

$ ls -lh /usr/share/man/man5/terminfo.5.gz 
-r--r--r--  1 root  wheel    34K Jun 21  2018 /usr/share/man/man5/terminfo.5.gz
 
$ ls -lh /usr/local/man/man5/terminfo.5.gz
-rw-r--r--  1 root  wheel    35K Aug 22  2019 /usr/local/man/man5/terminfo.5.gz
 
$ diff /usr/share/man/man5/terminfo.5.gz /usr/local/man/man5/terminfo.5.gz 
Binary files /usr/share/man/man5/terminfo.5.gz and /usr/local/man/man5/terminfo.5.gz differ
 
$ man /usr/local/man/man5/terminfo.5.gz:
         A number of escape sequences are provided in the string valued
         capabilities for easy encoding of characters there:
  
         *   Both \E and \e map to an ESCAPE character,
         *   ^x maps to a control-x for any appropriate x, and
         *   the sequences
                 \n, \l, \r, \t, \b, \f, and \s
             produce
             newline, line-feed, return, tab, backspace, form-feed, and space,
             respectively.


         X/Open Curses does not say what "appropriate x" might be.  In practice,
         that is a printable ASCII graphic character.  The special case "^?" is
         interpreted as DEL (127).  In all other cases, the character value is
         AND'd with 0x1f, mapping to ASCII control codes in the range 0 through
         31.
  
         Other escapes include
         *   \^ for ^,
         *   \\ for \,
         *   \, for comma,
         *   \: for :,
         *   and \0 for null.
  
             \0 will produce \200, which does not terminate a string but behaves
             as a null character on most terminals, providing CS7 is specified.
             See stty(1).

$ man /usr/share/man/man5/terminfo.5.gz:
       A number of escape sequences are provided in the string-valued
       capabilities for easy encoding of control characters there.  

       \E maps to
       an ESC character, ^X maps to a control-X for any appropriate X, and the
       sequences \n \r \t \b \f map to linefeed, return, tab, backspace, and
       formfeed, respectively.  Finally, characters may be given as three octal
       digits after a \, and the characters ^ and \ may be given as \^ and \\.
       If it is necessary to place a : in a capability it must be escaped as \:
       or be encoded as \072.  If it is necessary to place a NUL character in a
       string capability it must be encoded as \200.  (The routines that deal
       with termcap use C strings and strip the high bits of the output very
       late, so that a \200 comes out as a \000 would.)

$ man -w -a termcap
/usr/share/man/man3/termcap.3.gz
/usr/share/man/man5/termcap.5.gz

$ man /usr/share/man/man3/termcap.3.gz 

curs_termcap(3X)                                              curs_termcap(3X)

NAME
       PC, UP, BC, ospeed, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs -
       direct curses interface to the terminfo capability database

---- snip -----

$ man /usr/share/man/man5/termcap.5.gz:

TERMCAP(5)                FreeBSD File Formats Manual               TERMCAP(5)

NAME
     termcap – terminal capability data base

SYNOPSIS
     termcap

---- snip ----

     A number of escape sequences are provided in the string-valued
     capabilities for easy encoding of control characters there.  \E maps to
     an ESC character, ^X maps to a control-X for any appropriate X, and the
     sequences \n \r \t \b \f map to linefeed, return, tab, backspace, and
     formfeed, respectively.  Finally, characters may be given as three octal
     digits after a \, and the characters ^ and \ may be given as \^ and \\.
     If it is necessary to place a : in a capability it must be escaped as \:
     or be encoded as \072.  If it is necessary to place a NUL character in a
     string capability it must be encoded as \200.  (The routines that deal
     with termcap use C strings and strip the high bits of the output very
     late, so that a \200 comes out as a \000 would.)

man kbdmap(1)

BUGS
     The kbdmap and vidfont utilities work only on a **(virtual) console** 
     and not with X11.

man getcap(3)
      String capability values may contain any character.  Non-printable ASCII
      codes, new lines, and colons may be conveniently represented by the use
      of escape sequences:
  
       ^X        ('X' & 037)          control-X
       \b, \B    (ASCII 010)          backspace
       \t, \T    (ASCII 011)          tab
       \n, \N    (ASCII 012)          line feed (newline)
       \f, \F    (ASCII 014)          form feed
       \r, \R    (ASCII 015)          carriage return
       \e, \E    (ASCII 027)          escape
       \c, \C    (:)                  colon
       \\        (\)                  back slash
       \^        (^)                  caret
       \nnn      (ASCII octal nnn)

man terminfo(5)
         A number of escape sequences are provided in the string valued
         capabilities for easy encoding of characters there.  Both \E and \e map
         to an ESCAPE character, ^x maps to a control-x for any appropriate x,
         and the sequences \n \l \r \t \b \f \s give a newline, line-feed,
         return, tab, backspace, form-feed, and space.  


     Predefined Capabilities
         The following is a complete table of the capabilities included in a
         terminfo description block and available to terminfo-using code.  In
         each line of the table,
  
         The variable is the name by which the programmer (at the terminfo
         level) accesses the capability.
  
         The capname is the short name used in the text of the database, and is
         used by a person updating the database.  Whenever possible, capnames
         are chosen to be the same as or similar to the ANSI X3.64-1979 standard
         (now superseded by ECMA-48, which uses identical or very similar
         names).  Semantics are also intended to match those of the
         specification.
  
         The termcap code is the old termcap capability name (some capabilities
         are new, and have names which termcap did not originate).
  
         Capability names have no hard length limit, but an informal limit of 5
         characters has been adopted to keep them short and to allow the tabs in
         the source file Caps to line up nicely.
  
         Finally, the description field attempts to convey the semantics of the
         capability.  You may find some codes in the description field:
  
         (P)    indicates that padding may be specified
         #[1-9] in the description field indicates that the string is passed
                through tparm with parms as given (#i).
         (P*)   indicates that padding may vary in proportion to the number of
                lines affected
         (#i)   indicates the ith parameter.


         These are the boolean capabilities:
         ---- snip ----

         These are the numeric capabilities:
         ---- snip ----

         The following numeric capabilities are present in the SVr4.0 term
         structure, but are not yet documented in the man page.  They came in
         with SVr4's printer support.
         ---- snip ----

         These are the string capabilities:

                   Variable            Cap-     TCap   Description
                    String             name     Code
         ---- snip ----
           clear_all_tabs              tbc      ct     clear all tab stops (P)
         ---- snip ----
           clear_screen                clear    cl     clear screen and home
                                                       cursor (P*)
           clr_bol                     el1      cb     Clear to beginning of
                                                       line
           clr_eol                     el       ce     clear to end of line
                                                       (P)
           clr_eos                     ed       cd     clear to end of screen
                                                       (P*)
           column_address              hpa      ch     horizontal position
                                                       #1, absolute (P)
         ---- snip ----

           cursor_address              cup      cm     move to row #1 columns
                                                       #2
           cursor_down                 cud1     do     down one line
           cursor_home                 home     ho     home cursor (if no
                                                       cup)
         ---- snip ----
           enter_blink_mode            blink    mb     turn on blinking
           enter_bold_mode             bold     md     turn on bold (extra
                                                       bright) mode
           enter_ca_mode               smcup    ti     string to start
                                                       programs using cup
         ---- snip ----
           enter_shadow_mode           sshm     ZM     Enter shadow-print
                                                       mode
           enter_standout_mode         smso     so     begin standout mode
           enter_subscript_mode        ssubm    ZN     Enter subscript mode
           enter_superscript_mode      ssupm    ZO     Enter superscript mode
           enter_underline_mode        smul     us     begin underline mode
         ---- snip ----
           exit_attribute_mode         sgr0     me     turn off all
                                                       attributes
           exit_ca_mode                rmcup    te     strings to end
                                                       programs using cup
           exit_delete_mode            rmdc     ed     end delete mode
           exit_doublewide_mode        rwidm    ZQ     End double-wide mode
           exit_insert_mode            rmir     ei     exit insert mode
           exit_italics_mode           ritm     ZR     End italic mode
           exit_leftward_mode          rlm      ZS     End left-motion mode
           exit_micro_mode             rmicm    ZT     End micro-motion mode
           exit_shadow_mode            rshm     ZU     End shadow-print mode
           exit_standout_mode          rmso     se     exit standout mode
         ---- snip ----
           newline                     nel      nw     newline (behave like
                                                       cr followed by lf)
         ---- snip ----
           set_background              setb     Sb     Set background color #1
         ---- snip ----
           set_foreground              setf     Sf     Set foreground color #1
         ---- snip ----

         The following string capabilities are present in the SVr4.0 term
         structure, but were originally not documented in the man page.
  
  
                    Variable            Cap-       TCap   Description
                     String             name       Code

                    ---- snip ----
            set_a_background            setab      AB     Set background
                                                          color to #1, using
                                                          ANSI escape
            set_a_foreground            setaf      AF     Set foreground
                                                          color to #1, using
                                                          ANSI escape
                    ---- snip ----


          The XSI Curses standard added these hardcopy capabilities.  They were
          used in some post-4.1 versions of System V curses, e.g., Solaris 2.5
          and IRIX 6.x.  Except for YI, the ncurses termcap names for them are
          invented.  According to the XSI Curses standard, they have no termcap
          names.  If your compiled terminfo entries use these, they may not be
          binary-compatible with System V terminfo entries after SVr4.1; beware!

man user_caps(5)
             using a list of extended key names, ask tigetstr(3X) for their
             values, and
  
             given the list of values, ask key_defined(3X) for the key-code
             which would be returned for those keys by wgetch(3X).

man cat(1)
       -v      Display non-printing characters so they are visible.  Control
               characters print as ‘^X’ for control-X; the delete character
               (octal 0177) prints as ‘^?’.  Non-ASCII characters (with the high
               bit set) are printed as ‘M-’ (for meta) followed by the character
               for the low 7 bits.

+-----------------+-------+------------+-------------------------------+
| Sequence | C1   | Short | Name       | Effect                        |
+----------+------+-------+------------+-------------------------------+
|                                                                      |
|                       ---- snip ----                                 |
|                                                                      |
| ESC [    | 0x9B | CSI   | Control    | Most of the useful sequences. |
|          |      |       | Sequence   |                               |
|          |      |       | Introducer |                               | 
+----------+------+-------+------------+-------------------------------+

+----------+-----+-----+----------------+--------+--------+-------------+---------------------------+
| Seq,     |     |     | Acronym        |        |        | C           | Description               |
| aka      | Dec | Hex | (Abbreviation) | Symbol | Name   | Programming |                           |
| Caret    |     |     |                |        |        | Language,   |                           |
| notation |     |     |                |        |        | aka         |                           |
|          |     |     |                |        |        | C escape    |                           |
+----------+-----+-----+----------------+--------+--------+-------------+---------------------------+
|                                                                                                   |
|                                     ---- snip ----                                                |
|                                                                                                   |
+----------+-----+-----+----------------+--------+--------+-------------+---------------------------+
| ^[       | 27  | 1B  | ESC            | ␛     | Escape | \e          | Alters the                |
|          |     |     |                |        |        | *[NOTE]     | the meaning of a          |
|          |     |     |                |        |        |             | limited number            |
|          |     |     |                |        |        |             | of following              |
|          |     |     |                |        |        |             | bytes.                    |
|          |     |     |                |        |        |             |                           |
|          |     |     |                |        |        |             | Nowadays this is          |
|          |     |     |                |        |        |             | almost always used        |
|          |     |     |                |        |        |             | to introduce an           |
|          |     |     |                |        |        |             | **ANSI escape sequence.** |
|                                                                                                   |
|                                                                                                   |
|                                     ---- snip ----                                                |
|                                                                                                   |
+----------+-----+-----+----------------+--------+--------+-------------+---------------------------+

*[NOTE]
For the C Programming Language:
The '\e' escape sequence is not part of ISO C and many other language specifications.
However, it is understood by several compilers, including GCC (GNU Compiler Collection).

+------+-----+-----+------+------------+-----------------------------------------------------------+
| ESC+ | Dec | Hex | Abbr | Name       | Description                                               |
+------+-----+-----+------+------------+-----------------------------------------------------------+
|                                                                                                  | 
|                                  ---- snip ----                                                  |
|                                                                                                  |
+------+-----+-----+------+------------+-----------------------------------------------------------+
| [    | 155 | 9B  | CSI  | Control    | Used to introduce control sequences that take parameters. |
|      |     |     |      | Sequence   | Used for **ANSI escape sequences**.                       |
|      |     |     |      | Introducer |                                                           |
+------+-----+-----+------+------------+-----------------------------------------------------------+
|                                                                                                  |
|                                  ---- snip ----                                                  |
|                                                                                                  |
+------+-----+-----+------+----------+--------+----------------------------------------------------+

+-----+-----+-----+---------+--------+--------+----------------------------------------------------+
| Seq | Dec | Hex | Acronym | Name   | C      |  Description                                       |
+-----+-----+-----+---------+--------+--------+----------------------------------------------------+
|                                                                                                  |
|                                      ---- snip ----                                              |
|                                                                                                  |
+-----+-----+-----+---------+--------+--------+----------------------------------------------------+
| ^[  | 27  | 1B  | ESC     | Escape |        | The **Esc key** on the keyboard will               |
|     |     |     |         |        |        | cause this character to be sent on                 |
|     |     |     |         |        |        | most systems.  It can be used in                   |
|     |     |     |         |        |        | software user interfaces to exit from              |
|     |     |     |         |        |        | a screen, menu, or mode, or in                     |
|     |     |     |         |        |        | device-control protocols (e.g., printers           |
|     |     |     |         |        |        | and terminals) to signal that what                 |
|     |     |     |         |        |        | follows is a **special command sequence**          |
|     |     |     |         |        |        | rather than normal text.  In systems based         |
|     |     |     |         |        |        | on ISO/IEC 2022, even if another set of            |
|     |     |     |         |        |        | C0 control codes are used, this octet is           |
|     |     |     |         |        |        | required to always represent the escape character. |
+-----+-----+-----+---------+--------+--------+----------------------------------------------------+
|                                                                                                  |
|                                      ---- snip ----                                              |
|                                                                                                  |
+-----+-----+-----+---------+--------+--------+----------------------------------------------------+

---- snip ----

The options are as follows:
  
---- snip ----

-e escape_char
        Sets the escape character for sessions with a pty (default: ‘~’).
        The escape character is only recognized at the beginning of a
        line.  The escape character followed by a dot (‘.’) closes the
        connection; followed by control-Z suspends the connection; and
        followed by itself sends the escape character once.  Setting the
        character to “none” disables any escapes and makes the session
        fully transparent.

---- snip ----

ESCAPE CHARACTERS

---- snip ----
~^Z     Background ssh.

curs_termcap(3X)
curses(3X)
curs_terminfo(3X)
curs_threads(3X)
ncurses(3X)
terminfo(5)
term_variables(3X)

$ locate curses.h | grep -w curses
/usr/include/curses.h
/usr/local/include/ncurses/curses.h

$ ls -lh /usr/include/curses.h
-r--r--r--  1 root  wheel 98K Apr  8  2021 /usr/include/curses.h

$ ls -lh /usr/local/include/ncurses/curses.h
-rw-r--r--  1 root  wheel 98K Oct  7 07:45 /usr/local/include/ncurses/curses.h

$ diff /usr/include/curses.h /usr/local/include/ncurses/curses.h | wc -l
     216

$ diff /usr/include/curses.h /usr/local/include/ncurses/curses.h | head
2c2
<  * Copyright 2018-2019,2020 Thomas E. Dickey                                *
---
>  * Copyright 2018-2020,2021 Thomas E. Dickey                                *
36c36
< /* $Id: curses.h.in,v 1.266 2020/02/08 10:51:53 tom Exp $ */
---
> /* $Id: curses.h.in,v 1.277 2021/09/24 16:07:37 tom Exp $ */
40a41,68
> /*

$ wc -l /usr/include/curses.h
    2113 /usr/include/curses.h
 
$ wc -l /usr/local/include/ncurses/curses.h
    2114 /usr/local/include/ncurses/curses.h

$ freebsd-version
12.0-RELEASE-p10
 
$ uname -a
FreeBSD freebsd3.my.domain 12.0-RELEASE-p10 FreeBSD 12.0-RELEASE-p10 GENERIC  amd64
 
$ ps $$
  PID TT  STAT    TIME COMMAND
53440  5  Ss   0:00.62 -tcsh (tcsh)
 
$ printf %s\\n "$SHELL"
/bin/tcsh
 
$ printf %s\\n "$TERM"
xterm-new

$ tset -s
Erase is backspace.
set noglob;
setenv TERM xterm-new;
setenv TERMCAP 'xterm-new:@7=\EOF:@8=\EOM:F1=\E[23~:F2=\E[24~:K2=\EOE:Km=\E[M:k1=\EOP:k2=\EOQ:k3=\EOR:k4=\EOS:k5=\E[15~:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:k;=\E[21~:kI=\E[2~:kN=\E[6~:kP=\E[5~:kd=\EOB:kh=\EOH:kl=\EOD:kr=\EOC:ku=\EOA:am:bs:km:mi:ms:ut:xn:AX:Co#8:co#80:kn#12:li#24:pa#64:AB=\E[4%dm:AF=\E[3%dm:AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:ae=\E(B:al=\E[L:as=\E(0:bl=^G:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:cm=\E[%i%d;%dH:cs=\E[%i%d;%dr:ct=\E[3g:dc=\E[P:dl=\E[M:ei=\E[4l:ho=\E[H:im=\E[4h:is=\E[\041p\E[?3;4l\E[4l\E>:kD=\E[3~:kb=^H:ke=\E[?1l\E>:ks=\E[?1h\E=:kB=\E[Z:le=^H:md=\E[1m:me=\E[m:ml=\El:mr=\E[7m:mu=\Em:nd=\E[C:op=\E[39;49m:rc=\E8:rs=\E[\041p\E[?3;4l\E[4l\E>:sc=\E7:se=\E[27m:sf=^J:so=\E[7m:sr=\EM:st=\EH:ue=\E[24m:up=\E[A:us=\E[4m:ve=\E[?12l\E[?25h:vi=\E[?25l:vs=\E[?12;25h:';
unset noglob;
 
$ stty
speed 38400 baud;
lflags: echoe echok echoke echoctl
iflags: -ixany -imaxbel -brkint
oflags: tab3
cflags: cs7 parenb
erase   
^H      
 
$ stty -a
speed 38400 baud; 34 rows; 144 columns;
lflags: icanon isig iexten echo echoe echok echoke -echonl echoctl
        -echoprt -altwerase -noflsh -tostop -flusho -pendin -nokerninfo
        -extproc
iflags: -istrip icrnl -inlcr -igncr ixon -ixoff -ixany -imaxbel -ignbrk
        -brkint -inpck -ignpar -parmrk
oflags: opost onlcr -ocrnl tab3 -onocr -onlret
cflags: cread cs7 parenb -parodd hupcl -clocal -cstopb -crtscts -dsrflow
        -dtrflow -mdmbuf
cchars: discard = ^O; dsusp = ^Y; eof = ^D; eol = <undef>;
        eol2 = <undef>; erase = ^H; erase2 = ^H; intr = ^C; kill = ^U;
        lnext = ^V; min = 1; quit = ^\; reprint = ^R; start = ^Q;
        status = ^T; stop = ^S; susp = ^Z; time = 0; werase = ^W;
 
$ stty -e
speed 38400 baud; 34 rows; 144 columns;
lflags: icanon isig iexten echo echoe echok echoke -echonl echoctl
        -echoprt -altwerase -noflsh -tostop -flusho -pendin -nokerninfo
        -extproc
iflags: -istrip icrnl -inlcr -igncr ixon -ixoff -ixany -imaxbel -ignbrk
        -brkint -inpck -ignpar -parmrk
oflags: opost onlcr -ocrnl tab3 -onocr -onlret
cflags: cread cs7 parenb -parodd hupcl -clocal -cstopb -crtscts -dsrflow
        -dtrflow -mdmbuf
discard dsusp   eof     eol     eol2    erase   erase2  intr    kill    
^O      ^Y      ^D      <undef> <undef> ^H      ^H      ^C      ^U      
lnext   min     quit    reprint start   status  stop    susp    time    
^V      1       ^\      ^R      ^Q      ^T      ^S      ^Z      0       
werase  
^W      
 
$ stty -g
gfmt1:cflag=5a00:iflag=300:lflag=5cf:oflag=7:discard=f:dsusp=19:eof=4:eol=ff:eol2=ff:erase=8:erase2=8:intr=3:kill=15:lnext=16:min=1:quit=1c:reprint=12:start=11:status=14:stop=13:susp=1a:time=0:werase=17:ispeed=38400:ospeed=38400
 
$ stty all
speed 38400 baud; 34 rows; 144 columns;
lflags: icanon isig iexten echo echoe echok echoke -echonl echoctl
        -echoprt -altwerase -noflsh -tostop -flusho -pendin -nokerninfo
        -extproc
iflags: -istrip icrnl -inlcr -igncr ixon -ixoff -ixany -imaxbel -ignbrk
        -brkint -inpck -ignpar -parmrk
oflags: opost onlcr -ocrnl tab3 -onocr -onlret
cflags: cread cs7 parenb -parodd hupcl -clocal -cstopb -crtscts -dsrflow
        -dtrflow -mdmbuf
discard dsusp   eof     eol     eol2    erase   erase2  intr    kill    
^O      ^Y      ^D      <undef> <undef> ^H      ^H      ^C      ^U      
lnext   min     quit    reprint start   status  stop    susp    time    
^V      1       ^\      ^R      ^Q      ^T      ^S      ^Z      0       
werase  
^W      
 
$ tty
/dev/pts/5
 
$ bindkey | wc -l
     155
 
$ bindkey | grep -i esc
 
$ bindkey | grep -i control
 
$ bindkey | grep -i ctrl
 
$ bindkey | grep '\[' | wc -l
      22
 
$ bindkey | grep '\[' 
"^["           ->  vi-cmd-mode
"^["           ->  sequence-lead-in
"["            ->  sequence-lead-in
"^[[A"         -> history-search-backward
"^[[B"         -> history-search-forward
"^[[C"         -> forward-char
"^[[D"         -> backward-char
"^[[H"         -> beginning-of-line
"^[[F"         -> end-of-line
"^[OA"         -> history-search-backward
"^[OB"         -> history-search-forward
"^[OC"         -> forward-char
"^[OD"         -> backward-char
"^[OH"         -> beginning-of-line
"^[OF"         -> end-of-line
"^[?"          -> run-help
"[A"           -> history-search-backward
"[B"           -> history-search-forward
"[C"           -> forward-char
"[D"           -> backward-char
"[H"           -> beginning-of-line
"[F"           -> end-of-line
 
$ bindkey | grep '\[' | grep 'sequence-lead-in'
"^["           ->  sequence-lead-in
"["            ->  sequence-lead-in
 
$ bindkey -l | wc -l
     246
 
$ bindkey -l 
backward-char
          Move back a character
backward-delete-char
          Delete the character behind cursor
backward-delete-word
          Cut from beginning of current word to cursor - saved in cut buffer
backward-kill-line
          Cut from beginning of line to cursor - save in cut buffer
backward-word
          Move to beginning of current word
beginning-of-line
          Move to beginning of line
capitalize-word
          Capitalize the characters from cursor to end of current word
change-case
          Vi change case of character under cursor and advance one character
change-till-end-of-line
          Vi change to end of line
clear-screen
          Clear screen leaving current line on top
complete-word
          Complete current word
complete-word-fwd
          Tab forward through files
complete-word-back
          Tab backward through files
complete-word-raw
          Complete current word ignoring programmable completions
copy-prev-word
          Copy current word to cursor
copy-region-as-kill
          Copy area between mark and cursor to cut buffer
dabbrev-expand
          Expand to preceding word for which this is a prefix
delete-char
          Delete character under cursor
delete-char-or-eof
          Delete character under cursor or signal end of file on an empty line
delete-char-or-list
          Delete character under cursor or list completions if at end of line
delete-char-or-list-or-eof
          Delete character under cursor, list completions or signal end of file
delete-word
          Cut from cursor to end of current word - save in cut buffer
digit
          Adds to argument if started or enters digit
digit-argument
          Digit that starts argument
down-history
          Move to next history line
downcase-word
          Lowercase the characters from cursor to end of current word
end-of-file
          Indicate end of file
end-of-line
          Move cursor to end of line
exchange-point-and-mark
          Exchange the cursor and mark
expand-glob
          Expand file name wildcards
expand-history
          Expand history escapes
expand-line
          Expand the history escapes in a line
expand-variables
          Expand variables
forward-char
          Move forward one character
forward-word
          Move forward to end of current word
gosmacs-transpose-chars
          Exchange the two characters before the cursor
history-search-backward
          Search in history backward for line beginning as current
history-search-forward
          Search in history forward for line beginning as current
insert-last-word
          Insert last item of previous command
i-search-fwd
          Incremental search forward
i-search-back
          Incremental search backward
keyboard-quit
          Clear line
kill-line
          Cut to end of line and save in cut buffer
kill-region
          Cut area between mark and cursor and save in cut buffer
kill-whole-line
          Cut the entire line and save in cut buffer
list-choices
          List choices for completion
list-choices-raw
          List choices for completion overriding programmable completion
list-glob
          List file name wildcard matches
list-or-eof
          List choices for completion or indicate end of file if empty line
load-average
          Display load average and current process status
magic-space
          Expand history escapes and insert a space
newline
          Execute command
newline-and-hold
          Execute command and keep current line
newline-and-down-history
          Execute command and move to next history line
normalize-path
          Expand pathnames, eliminating leading .'s and ..'s
normalize-command
          Expand commands to the resulting pathname or alias
overwrite-mode
          Switch from insert to overwrite mode or vice versa
prefix-meta
          Add 8th bit to next character typed
quoted-insert
          Add the next character typed to the line verbatim
redisplay
          Redisplay everything
run-fg-editor
          Restart stopped editor
run-help
          Look for help on current command
self-insert-command
          This character is added to the line
sequence-lead-in
          This character is the first in a character sequence
set-mark-command
          Set the mark at cursor
spell-word
          Correct the spelling of current word
spell-line
          Correct the spelling of entire line
stuff-char
          Send character to tty in cooked mode
toggle-literal-history
          Toggle between literal and lexical current history line
transpose-chars
          Exchange the character to the left of the cursor with the one under
transpose-gosling
          Exchange the two characters before the cursor
tty-dsusp
          Tty delayed suspend character
tty-flush-output
          Tty flush output character
tty-sigintr
          Tty interrupt character
tty-sigquit
          Tty quit character
tty-sigtsusp
          Tty suspend character
tty-start-output
          Tty allow output character
tty-stop-output
          Tty disallow output character
undefined-key
          Indicates unbound character
universal-argument
          Emacs universal argument (argument times 4)
up-history
          Move to previous history line
upcase-word
          Uppercase the characters from cursor to end of current word
vi-beginning-of-next-word
          Vi goto the beginning of next word
vi-add
          Vi enter insert mode after the cursor
vi-add-at-eol
          Vi enter insert mode at end of line
vi-chg-case
          Vi change case of character under cursor and advance one character
vi-chg-meta
          Vi change prefix command
vi-chg-to-eol
          Vi change to end of line
vi-cmd-mode
          Enter vi command mode (use alternative key bindings)
vi-cmd-mode-complete
          Vi command mode complete current word
vi-delprev
          Vi move to previous character (backspace)
vi-delmeta
          Vi delete prefix command
vi-endword
          Vi move to the end of the current space delimited word
vi-eword
          Vi move to the end of the current word
vi-char-back
          Vi move to the character specified backward
vi-char-fwd
          Vi move to the character specified forward
vi-charto-back
          Vi move up to the character specified backward
vi-charto-fwd
          Vi move up to the character specified forward
vi-insert
          Enter vi insert mode
vi-insert-at-bol
          Enter vi insert mode at beginning of line
vi-repeat-char-fwd
          Vi repeat current character search in the same search direction
vi-repeat-char-back
          Vi repeat current character search in the opposite search direction
vi-repeat-search-fwd
          Vi repeat current search in the same search direction
vi-repeat-search-back
          Vi repeat current search in the opposite search direction
vi-replace-char
          Vi replace character under the cursor with the next character typed
vi-replace-mode
          Vi replace mode
vi-search-back
          Vi search history backward
vi-search-fwd
          Vi search history forward
vi-substitute-char
          Vi replace character under the cursor and enter insert mode
vi-substitute-line
          Vi replace entire line
vi-word-back
          Vi move to the previous word
vi-word-fwd
          Vi move to the next word
vi-undo
          Vi undo last change
vi-zero
          Vi goto the beginning of line
which-command
          Perform which of current command
yank
          Paste cut buffer at cursor position
yank-pop
          Replace just-yanked text with yank from earlier kill
e_copy_to_clipboard
          (WIN32 only) Copy cut buffer to system clipboard
e_paste_from_clipboard
          (WIN32 only) Paste clipboard buffer at cursor position
e_dosify_next
          (WIN32 only) Convert each '/' in next word to '\\'
e_dosify_prev
          (WIN32 only) Convert each '/' in previous word to '\\'
e_page_up
          (WIN32 only) Page visible console window up
e_page_down
          (WIN32 only) Page visible console window down
 
$ bindkey -l | grep -A1 'sequence-lead-in'
sequence-lead-in
          This character is the first in a character sequence
 
$ bindkdy -a | wc -l
bindkdy: Command not found.
       0
 
$ bindkey -a | wc -l
     155
 
$ bindkey -a 
Standard key bindings
"^@"           ->  is undefined
"^A"           ->  beginning-of-line
"^B"           ->  backward-char
"^C"           ->  tty-sigintr
"^D"           ->  list-or-eof
"^E"           ->  end-of-line
"^F"           ->  forward-char
"^G"           ->  list-glob
"^H"           ->  backward-delete-char
"^I"           ->  complete-word
"^J"           ->  newline
"^K"           ->  kill-line
"^L"           ->  clear-screen
"^M"           ->  newline
"^N"           ->  down-history
"^O"           ->  tty-flush-output
"^P"           ->  up-history
"^Q"           ->  tty-start-output
"^R"           ->  redisplay
"^S"           ->  tty-stop-output
"^T"           ->  transpose-chars
"^U"           ->  backward-kill-line
"^V"           ->  quoted-insert
"^W"           ->  backward-delete-word
"^X"           ->  expand-line
"^Y"           ->  tty-dsusp
"^Z"           ->  tty-sigtsusp
"^["           ->  vi-cmd-mode
"^\"           ->  tty-sigquit
" "  to "~"    ->  self-insert-command
"^?"           ->  backward-delete-char
"B!" to "C?"   ->  self-insert-command
Alternative key bindings
"^@"           ->  is undefined
"^A"           ->  beginning-of-line
"^B"           ->  is undefined
"^C"           ->  tty-sigintr
"^D"           ->  list-choices
"^E"           ->  end-of-line
"^F"           ->  is undefined
"^G"           ->  list-glob
"^H"           ->  backward-char
"^I"           ->  vi-cmd-mode-complete
"^J"           ->  newline
"^K"           ->  kill-line
"^L"           ->  clear-screen
"^M"           ->  newline
"^N"           ->  down-history
"^O"           ->  tty-flush-output
"^P"           ->  up-history
"^Q"           ->  tty-start-output
"^R"           ->  redisplay
"^S"           ->  tty-stop-output
"^T"           ->  is undefined
"^U"           ->  backward-kill-line
"^V"           ->  is undefined
"^W"           ->  backward-delete-word
"^X"           ->  expand-line
"^["           ->  sequence-lead-in
"^\"           ->  tty-sigquit
" "            ->  forward-char
"!"            ->  expand-history
"$"            ->  end-of-line
"*"            ->  expand-glob
"+"            ->  down-history
","            ->  vi-repeat-char-back
"-"            ->  up-history
"."            ->  is undefined
"/"            ->  vi-search-fwd
"0"            ->  vi-zero
"1"  to "9"    ->  digit-argument
":"            ->  is undefined
";"            ->  vi-repeat-char-fwd
"?"            ->  vi-search-back
"@"            ->  is undefined
"A"            ->  vi-add-at-eol
"B"            ->  vi-word-back
"C"            ->  change-till-end-of-line
"D"            ->  kill-line
"E"            ->  vi-endword
"F"            ->  vi-char-back
"I"            ->  vi-insert-at-bol
"J"            ->  history-search-forward
"K"            ->  history-search-backward
"N"            ->  vi-repeat-search-back
"O"            ->  sequence-lead-in
"R"            ->  vi-replace-mode
"S"            ->  vi-substitute-line
"T"            ->  vi-charto-back
"U"            ->  is undefined
"V"            ->  expand-variables
"W"            ->  vi-word-fwd
"X"            ->  backward-delete-char
"["            ->  sequence-lead-in
"\^"           ->  beginning-of-line
"a"            ->  vi-add
"b"            ->  backward-word
"c"            ->  vi-chg-meta
"d"            ->  vi-delmeta
"e"            ->  vi-eword
"f"            ->  vi-char-fwd
"g"            ->  is undefined
"h"            ->  backward-char
"i"            ->  vi-insert
"j"            ->  down-history
"k"            ->  up-history
"l"            ->  forward-char
"m"            ->  is undefined
"n"            ->  vi-repeat-search-fwd
"r"            ->  vi-replace-char
"s"            ->  vi-substitute-char
"t"            ->  vi-charto-fwd
"u"            ->  vi-undo
"v"            ->  expand-variables
"w"            ->  vi-beginning-of-next-word
"x"            ->  delete-char-or-eof
"~"            ->  change-case
"^?"           ->  backward-delete-char
"B?"           ->  run-help
"C"           ->  sequence-lead-in
"C"           ->  sequence-lead-in
Multi-character bindings
"^[[A"         -> history-search-backward
"^[[B"         -> history-search-forward
"^[[C"         -> forward-char
"^[[D"         -> backward-char
"^[[H"         -> beginning-of-line
"^[[F"         -> end-of-line
"^[OA"         -> history-search-backward
"^[OB"         -> history-search-forward
"^[OC"         -> forward-char
"^[OD"         -> backward-char
"^[OH"         -> beginning-of-line
"^[OF"         -> end-of-line
"^[?"          -> run-help
"[A"           -> history-search-backward
"[B"           -> history-search-forward
"[C"           -> forward-char
"[D"           -> backward-char
"[H"           -> beginning-of-line
"[F"           -> end-of-line
"OA"           -> history-search-backward
"OB"           -> history-search-forward
"OC"           -> forward-char
"OD"           -> backward-char
"OH"           -> beginning-of-line
"OF"           -> end-of-line
Arrow key bindings
down           -> history-search-forward
up             -> history-search-backward
left           -> backward-char
right          -> forward-char
home           -> beginning-of-line
end            -> end-of-line
 
$ bindkey -a | grep -n 'sequence-lead-in'
60:"^["           ->  sequence-lead-in
87:"O"            ->  sequence-lead-in
95:"["            ->  sequence-lead-in
121:"Ï"           ->  sequence-lead-in
122:"Û"           ->  sequence-lead-in

$ printf '%d\n' '"^\'
94
 
$ printf '%d\n' '"^['
94
$ 
$ printf '%d\n' '\^['
printf: \^[: expected numeric value
0
 
$ printf '%d\n' 
0
 
$ printf '%d\n' 6
6
 
$ printf '%d\n' a
printf: a: expected numeric value
0
 
$ printf '%d\n' '\a'
printf: \a: expected numeric value
0
 
$ printf '%d\n' 'a'
printf: a: expected numeric value
0
 
$ printf '%s\n' "${red//$'\e'/\\E}"
Missing '}'.
 
$ tput xterm-clear clear | od -c
0000000  033   [   H 033   [   2   J                                    
0000007
 
$ tput xterm-clear clear | od -x
0000000      5b1b    1b48    325b    004a                                
0000007
 
$ tput xterm-clear clear | od -d
0000000     23323    6984   12891      74                                
0000007
 
$ tput xterm-clear clear | od 
0000000    055433  015510  031133  000112                                
0000007
 
$ tput xterm-clear clear | od -b
0000000   033 133 110 033 133 062 112                                    
0000007
 
$ tput xterm-clear clear | od -c
0000000  033   [   H 033   [   2   J                                    
0000007
 
$ tput xterm-clear clear | od -a
0000000  esc   [   H esc   [   2   J                                    
0000007
 
$ tput xterm-clear clear | od -t a
0000000  esc   [   H esc   [   2   J                                    
0000007
 
$ tput xterm-clear clear | od -v
0000000    055433  015510  031133  000112                                
0000007
 
$ tput xterm-clear clear | od -a
0000000  esc   [   H esc   [   2   J                                    
0000007
 
$ tput xterm-clear clear | od -a -v
0000000  esc   [   H esc   [   2   J                                    
0000007
 
$ tput xterm-clear clear | od 
0000000    055433  015510  031133  000112                                
0000007
 
$ tput xterm-clear clear | hexdump -c
0000000 033   [   H 033   [   2   J                                    
0000007
 
$ tput xterm-clear clear | hexdump -b
0000000 033 133 110 033 133 062 112                                    
0000007
 
$ tput xterm-clear clear | hexdump -C
00000000  1b 5b 48 1b 5b 32 4a                              |.[H.[2J|
00000007
 
$ tput xterm-clear clear | hexdump -o
0000000  055433  015510  031133  000112                                
0000007
 
$ tput xterm-clear clear | hexdump -v
0000000 5b1b 1b48 325b 004a                    
0000007
 
$ tput xterm-clear clear | hexdump -v -C
00000000  1b 5b 48 1b 5b 32 4a                              |.[H.[2J|
00000007
 
$ tput xterm-clear clear | hexdump -v -o
0000000  055433  015510  031133  000112                                
0000007
 
$ tput xterm-clear clear | hexdump -v -b
0000000 033 133 110 033 133 062 112                                    
0000007
 
$ tput xterm-clear clear | hexdump -v -x
0000000    5b1b    1b48    325b    004a                                
0000007

$ tset -S
Erase is backspace.
xterm-new xterm-new:@7=\EOF:@8=\EOM:F1=\E[23~:F2=\E[24~:K2=\EOE:Km=\E[M:k1=\EOP:k2=\EOQ:k3=\EOR:k4=\EOS:k5=\E[15~:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:k;=\E[21~:kI=\E[2~:kN=\E[6~:kP=\E[5~:kd=\EOB:kh=\EOH:kl=\EOD:kr=\EOC:ku=\EOA:am:bs:km:mi:ms:ut:xn:AX:Co#8:co#80:kn#12:li#24:pa#64:AB=\E[4%dm:AF=\E[3%dm:AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:ae=\E(B:al=\E[L:as=\E(0:bl=^G:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:cm=\E[%i%d;%dH:cs=\E[%i%d;%dr:ct=\E[3g:dc=\E[P:dl=\E[M:ei=\E[4l:ho=\E[H:im=\E[4h:is=\E[\041p\E[?3;4l\E[4l\E>:kD=\E[3~:kb=^H:ke=\E[?1l\E>:ks=\E[?1h\E=:kB=\E[Z:le=^H:md=\E[1m:me=\E[m:ml=\El:mr=\E[7m:mu=\Em:nd=\E[C:op=\E[39;49m:rc=\E8:rs=\E[\041p\E[?3;4l\E[4l\E>:sc=\E7:se=\E[27m:sf=^J:so=\E[7m:sr=\EM:st=\EH:ue=\E[24m:up=\E[A:us=\E[4m:ve=\E[?12l\E[?25h:vi=\E[?25l:vs=\E[?12;25h:$ 
 
$ tset -s
Erase is backspace.
set noglob;
setenv TERM xterm-new;
setenv TERMCAP 'xterm-new:@7=\EOF:@8=\EOM:F1=\E[23~:F2=\E[24~:K2=\EOE:Km=\E[M:k1=\EOP:k2=\EOQ:k3=\EOR:k4=\EOS:k5=\E[15~:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:k;=\E[21~:kI=\E[2~:kN=\E[6~:kP=\E[5~:kd=\EOB:kh=\EOH:kl=\EOD:kr=\EOC:ku=\EOA:am:bs:km:mi:ms:ut:xn:AX:Co#8:co#80:kn#12:li#24:pa#64:AB=\E[4%dm:AF=\E[3%dm:AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:ae=\E(B:al=\E[L:as=\E(0:bl=^G:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:cm=\E[%i%d;%dH:cs=\E[%i%d;%dr:ct=\E[3g:dc=\E[P:dl=\E[M:ei=\E[4l:ho=\E[H:im=\E[4h:is=\E[\041p\E[?3;4l\E[4l\E>:kD=\E[3~:kb=^H:ke=\E[?1l\E>:ks=\E[?1h\E=:kB=\E[Z:le=^H:md=\E[1m:me=\E[m:ml=\El:mr=\E[7m:mu=\Em:nd=\E[C:op=\E[39;49m:rc=\E8:rs=\E[\041p\E[?3;4l\E[4l\E>:sc=\E7:se=\E[27m:sf=^J:so=\E[7m:sr=\EM:st=\EH:ue=\E[24m:up=\E[A:us=\E[4m:ve=\E[?12l\E[?25h:vi=\E[?25l:vs=\E[?12;25h:';
unset noglob;

$ infocmp 
#     Reconstructed via infocmp from file: /usr/local/share/misc/terminfo.db
xterm-new|modern xterm terminal emulator,
      am, bce, km, mc5i, mir, msgr, npc, xenl,
      colors#8, cols#80, it#8, lines#24, pairs#64,
      acsc=``aaffggiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{ { | | } }~~,
      bel=^G, blink=\E[5m, bold=\E[1m, cbt=\E[Z, civis=\E[?25l,
      clear=\E[H\E[2J, cnorm=\E[?12l\E[?25h, cr=\r,
      csr=\E[%i%p1%d;%p2%dr, cub=\E[%p1%dD, cub1=^H,
      cud=\E[%p1%dB, cud1=\n, cuf=\E[%p1%dC, cuf1=\E[C,
      cup=\E[%i%p1%d;%p2%dH, cuu=\E[%p1%dA, cuu1=\E[A,
      cvvis=\E[?12;25h, dch=\E[%p1%dP, dch1=\E[P, dim=\E[2m,
      dl=\E[%p1%dM, dl1=\E[M, ech=\E[%p1%dX, ed=\E[J, el=\E[K,
      el1=\E[1K, flash=\E[?5h$<100/>\E[?5l, home=\E[H,
      hpa=\E[%i%p1%dG, ht=^I, hts=\EH, ich=\E[%p1%d@,
      il=\E[%p1%dL, il1=\E[L, ind=\n, indn=\E[%p1%dS,
      invis=\E[8m, is2=\E[!p\E[?3;4l\E[4l\E>, kDC=\E[3;2~,
      kEND=\E[1;2F, kHOM=\E[1;2H, kIC=\E[2;2~, kLFT=\E[1;2D,
      kNXT=\E[6;2~, kPRV=\E[5;2~, kRIT=\E[1;2C, ka1=\EOw,
      ka3=\EOy, kb2=\EOu, kbs=^H, kc1=\EOq, kc3=\EOs, kcbt=\E[Z,
      kcub1=\EOD, kcud1=\EOB, kcuf1=\EOC, kcuu1=\EOA,
      kdch1=\E[3~, kend=\EOF, kent=\EOM, kf1=\EOP, kf10=\E[21~,
      kf11=\E[23~, kf12=\E[24~, kf13=\E[1;2P, kf14=\E[1;2Q,
      kf15=\E[1;2R, kf16=\E[1;2S, kf17=\E[15;2~, kf18=\E[17;2~,
      kf19=\E[18;2~, kf2=\EOQ, kf20=\E[19;2~, kf21=\E[20;2~,
      kf22=\E[21;2~, kf23=\E[23;2~, kf24=\E[24;2~,
      kf25=\E[1;5P, kf26=\E[1;5Q, kf27=\E[1;5R, kf28=\E[1;5S,
      kf29=\E[15;5~, kf3=\EOR, kf30=\E[17;5~, kf31=\E[18;5~,
      kf32=\E[19;5~, kf33=\E[20;5~, kf34=\E[21;5~,
      kf35=\E[23;5~, kf36=\E[24;5~, kf37=\E[1;6P, kf38=\E[1;6Q,
      kf39=\E[1;6R, kf4=\EOS, kf40=\E[1;6S, kf41=\E[15;6~,
      kf42=\E[17;6~, kf43=\E[18;6~, kf44=\E[19;6~,
      kf45=\E[20;6~, kf46=\E[21;6~, kf47=\E[23;6~,
      kf48=\E[24;6~, kf49=\E[1;3P, kf5=\E[15~, kf50=\E[1;3Q,
      kf51=\E[1;3R, kf52=\E[1;3S, kf53=\E[15;3~, kf54=\E[17;3~,
      kf55=\E[18;3~, kf56=\E[19;3~, kf57=\E[20;3~,
      kf58=\E[21;3~, kf59=\E[23;3~, kf6=\E[17~, kf60=\E[24;3~,
      kf61=\E[1;4P, kf62=\E[1;4Q, kf63=\E[1;4R, kf7=\E[18~,
      kf8=\E[19~, kf9=\E[20~, khome=\EOH, kich1=\E[2~,
      kind=\E[1;2B, kmous=\E[<, knp=\E[6~, kpp=\E[5~,
      kri=\E[1;2A, mc0=\E[i, mc4=\E[4i, mc5=\E[5i, meml=\El,
      memu=\Em, mgc=\E[?69l, op=\E[39;49m, rc=\E8,
      rep=%p1%c\E[%p2%{1}%-%db, rev=\E[7m, ri=\EM,
      rin=\E[%p1%dT, ritm=\E[23m, rmacs=\E(B, rmam=\E[?7l,
      rmcup=\E[?1049l\E[23;0;0t, rmir=\E[4l, rmkx=\E[?1l\E>,
      rmm=\E[?1034l, rmso=\E[27m, rmul=\E[24m, rs1=\Ec,
      rs2=\E[!p\E[?3;4l\E[4l\E>, sc=\E7, setab=\E[4%p1%dm,
      setaf=\E[3%p1%dm,
      setb=\E[4%?%p1%{1}%=%t4%e%p1%{3}%=%t6%e%p1%{4}%=%t1%e%p1%{6}%=%t3%e%p1%d%;m,
      setf=\E[3%?%p1%{1}%=%t4%e%p1%{3}%=%t6%e%p1%{4}%=%t1%e%p1%{6}%=%t3%e%p1%d%;m,
      sgr=%?%p9%t\E(0%e\E(B%;\E[0%?%p6%t;1%;%?%p5%t;2%;%?%p2%t;4%;%?%p1%p3%|%t;7%;%?%p4%t;5%;%?%p7%t;8%;m,
      sgr0=\E(B\E[m, sitm=\E[3m, smacs=\E(0, smam=\E[?7h,
      smcup=\E[?1049h\E[22;0;0t,
      smglr=\E[?69h\E[%i%p1%d;%p2%ds, smir=\E[4h,
      smkx=\E[?1h\E=, smm=\E[?1034h, smso=\E[7m, smul=\E[4m,
      tbc=\E[3g, u6=\E[%i%d;%dR, u7=\E[6n,
      u8=\E[?%[;0123456789]c, u9=\E[c, vpa=\E[%i%p1%dd,

$ infocmp -K
#     Reconstructed via infocmp from file: /usr/local/share/misc/terminfo.db
# (untranslatable capabilities removed to fit entry within 1023 bytes)
xterm-new|modern xterm terminal emulator:\
      :am:bs:km:mi:ms:xn:\
      :co#80:it#8:li#24:\
      :AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:IC=\E[%d@:\
      :K1=\EOw:K2=\EOu:K3=\EOy:K4=\EOq:K5=\EOs:LE=\E[%dD:\
      :RI=\E[%dC:SF=\E[%dS:SR=\E[%dT:UP=\E[%dA:ae=\E(B:al=\E[L:\
      :as=\E(0:bl=^G:bt=\E[Z:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:\
      :cm=\E[%i%d;%dH:cr=\r:cs=\E[%i%d;%dr:ct=\E[3g:dc=\E[P:\
      :dl=\E[M:do=\n:ec=\E[%dX:ei=\E[4l:ho=\E[H:im=\E[4h:\
      :is=\E[!p\E[?3;4l\E[4l\E>:k1=\EOP:k2=\EOQ:k3=\EOR:\
      :k4=\EOS:k5=\E[15~:k6=\E[17~:k7=\E[18~:k8=\E[19~:\
      :k9=\E[20~:kD=\E[3~:kI=\E[2~:kN=\E[6~:kP=\E[5~:kb=^H:\
      :kd=\EOB:ke=\E[?1l\E>:kh=\EOH:kl=\EOD:kr=\EOC:\
      :ks=\E[?1h\E=:ku=\EOA:le=^H:mb=\E[5m:md=\E[1m:me=\E[0m:\
      :mh=\E[2m:mm=\E[?1034h:mo=\E[?1034l:mr=\E[7m:nd=\E[C:\
      :rc=\E8:sc=\E7:se=\E[27m:sf=\n:so=\E[7m:sr=\EM:st=\EH:ta=^I:\
      :te=\E[?1049l\E[23;0;0t:ti=\E[?1049h\E[22;0;0t:\
      :ue=\E[24m:up=\E[A:us=\E[4m:vb=\E[?5h\E[?5l:\
      :ve=\E[?12l\E[?25h:vi=\E[?25l:vs=\E[?12;25h:
 
$ stty -e
speed 38400 baud; 34 rows; 144 columns;
lflags: icanon isig iexten echo echoe echok echoke -echonl echoctl
        -echoprt -altwerase -noflsh -tostop -flusho -pendin -nokerninfo
        -extproc
iflags: -istrip icrnl -inlcr -igncr ixon -ixoff -ixany -imaxbel -ignbrk
        -brkint -inpck -ignpar -parmrk
oflags: opost onlcr -ocrnl tab3 -onocr -onlret
cflags: cread cs7 parenb -parodd hupcl -clocal -cstopb -crtscts -dsrflow
        -dtrflow -mdmbuf
discard dsusp   eof     eol     eol2    erase   erase2  intr    kill    
^O      ^Y      ^D      <undef> <undef> ^H      ^H      ^C      ^U      
lnext   min     quit    reprint start   status  stop    susp    time    
^V      1       ^\      ^R      ^Q      ^T      ^S      ^Z      0       
werase  
^W      

---- snip ----

Special Keys
    Xterm, like any VT100-compatible terminal emulator, has two modes for
    the special keys (cursor-keys, numeric keypad, and certain function-
    keys):

    *   normal mode, which makes the special keys transmit “useful”
        sequences such as the control sequence for cursor-up when pressing
        the up-arrow, and
  
    *   application mode, which uses a different control sequence that
        cannot be mistaken for the “useful” sequences.

    The main difference between the two modes is that normal mode sequences
    start with CSI (escape [) and application mode sequences start with SS3
    (escape O).
  
    The terminal is initialized into one of these two modes (usually the
    normal mode), based on the terminal description (termcap or terminfo).
    The terminal description also has capabilities (strings) defined for
    the keypad mode used in curses applications.
  
    There is a problem in using the terminal description for applications
    that are not intended to be full-screen curses applications: the
    definitions of special keys are only correct for this keypad mode.  For
    example, some shells (unlike ksh(1), which appears to be hard-coded,
    not even using termcap) allow their users to customize key-bindings,
    assigning shell actions to special keys.

---- snip ----

console_codes(4) - Linux manual page

console_codes(4)        Kernel Interfaces Manual        console_codes(4)

NAME
       console_codes - Linux console escape and control sequences

DESCRIPTION
       The Linux console implements a large subset of the VT102 and
       ECMA-48/ISO 6429/ANSI X3.64 terminal controls, plus certain
       private-mode sequences for changing the color palette, character-
       set mapping, and so on.  In the tabular descriptions below, the
       second column gives ECMA-48 or DEC mnemonics (the latter if
       prefixed with DEC) for the given function.  Sequences without a
       mnemonic are neither ECMA-48 nor VT102.

       After all the normal output processing has been done, and a
       stream of characters arrives at the console driver for actual
       printing, the first thing that happens is a translation from the
       code used for processing to the code used for printing.

       If the console is in **UTF-8 mode**, then the incoming bytes are
       first assembled into *16-bit Unicode codes*.  Otherwise, each byte
       is transformed according to the current mapping table (which
       translates it to a Unicode value).  See the *Character Sets*
       section below for discussion.

       In the normal case, the Unicode value is converted to a font
       index, and this is stored in video memory, so that the
       corresponding glyph (as found in video ROM) appears on the
       screen.  Note that the use of Unicode (and the design of the PC
       hardware) allows us to use 512 different glyphs simultaneously.

       If the current Unicode value is a **control character**, or we are
       currently processing an **escape sequence**, the value will treated
       **specially**.  Instead of being turned into a font index and rendered
       as a glyph, it may trigger cursor movement or other control functions.
       See the *Linux Console Controls* section below for discussion.

       It is generally not good practice to hard-wire terminal controls into
       programs.  Linux supports a *terminfo(5)* database of *terminal
       capabilities*.  Rather than emitting console escape sequences by hand,
       you will almost always want to use a terminfo-aware screen library or
       utility such as ncurses(3), tput(1), or reset(1).

Linux console controls
----------------------
    This section describes all the control characters and escape
    sequences that invoke special functions (i.e., anything other than
    writing a glyph at the current cursor location) on the Linux console.

    Control characters
    -------------------

    A character is a *control character* if (before transformation
    according to the mapping table) it has one of the following 14 codes:
    00 (NUL), 07 (BEL), 08 (BS), 09 (HT), 0a (LF), 0b (VT), 0c (FF), 0d (CR),
    0e(SO), 0f (SI), 18 (CAN), 1a (SUB), 1b (ESC), 7f (DEL).

    One can set a" "display control characters" mode (see below), and
    allow 07, 09, 0b, 18, 1a, 7f to be displayed as glyphs.
    On the other hand, in *UTF-8* mode all codes 00 - 1f are regarded as
    *control characters*, regardless of any "display control characters" mode.

    If we have a control character, it is acted upon immediately and then
    discarded (even in the middle of an escape sequence) and the escape
    sequence continues with the next character. 
    (However, ESC starts a new escape sequence, possibly aborting a previous
    unfinished one, and CAN and SUB abort any escape sequence.)

    The recognized **control characters** are BEL, BS, HT, LF, VT, FF, CR,
                                              SO, SI, CAN, SUB, ESC, DEL, CSI.  
    They do what one would expect:

    BEL (0x07, ^G)
           beeps;

    BS (0x08, ^H)
           backspaces one column (but not past the beginning of
           the line);

    HT (0x09, ^I)
           goes to the next tab stop or to the end of the line if
           there is no earlier tab stop;

    LF (0x0A, ^J)
    VT (0x0B, ^K)
    FF (0x0C, ^L)
           all give a linefeed,
           and if LF/NL (new-line mode) is set
           also a carriage return;

    CR (0x0D, ^M)
           gives a carriage return;

    SO (0x0E, ^N)
           activates the G1 character set;

    SI (0x0F, ^O)
           activates the G0 character set;

    CAN (0x18, ^X)
    SUB (0x1A, ^Z)
            interrupt escape sequences (abort escape sequences);

******** <<== My highliting 
    ESC (0x1B, ^[)
            starts an escape sequence;
******** <<== My highliting

    DEL (0x7F)
            is ignored;

******** <<== My highliting
    CSI (0x9B)
            is equivalent to ESC [.
******** <<== My highliting 

---- snip ----


    ECMA-48 CSI sequences (Control Sequence Introducer sequences) 
                          (a.k.a. Control Sequence Initiator sequences)
    -------------------------------------------------------------------
       CSI (or ESC [) is followed by a sequence of parameters, at most
       NPAR (16), that are decimal numbers separated by semicolons.

       An empty or absent parameter is taken to be 0.

       The sequence of parameters may be preceded by a single question mark.

       However, after CSI [ (or ESC [ [) a single character is read and
       this entire sequence is ignored.  (The idea is to ignore an
       echoed function key.)

---- snip ----

Character sets
--------------
       The kernel knows about 4 translations of bytes into console-
       screen symbols.  The four tables are: a) Latin1 -> PC, b) VT100
       graphics -> PC, c) PC -> PC, d) user-defined.

       There are two character sets, called G0 and G1, and one of them
       is the current character set.  (Initially G0.)  Typing ^N causes
       G1 to become current, ^O causes G0 to become current.

       These variables G0 and G1 point at a translation table, and can
       be changed by the user.  Initially they point at tables a) and
       b), respectively.  The sequences ESC ( B and ESC ( 0 and ESC ( U
       and ESC ( K cause G0 to point at translation table a), b), c),
       and d), respectively.  The sequences ESC ) B and ESC ) 0 and ESC
       ) U and ESC ) K cause G1 to point at translation table a), b),
       c), and d), respectively.

       The sequence ESC c causes a terminal reset, which is what you
       want if the screen is all garbled.  The oft-advised "echo ^V^O"
       will make only G0 current, but there is no guarantee that G0
       points at table a).  In some distributions there is a program
       reset(1) that just does "echo ^[c".  If your terminfo entry for
       the console is correct (and has an entry rs1=\Ec), then "tput
       reset" will also work.

       The user-defined mapping table can be set using mapscrn(8).  The
       result of the mapping is that if a symbol c is printed, the
       symbol s = map[c] is sent to the video memory.  The bitmap that
       corresponds to s is found in the character ROM, and can be
       changed using setfont(8).

---- snip ----

Comparisons with other terminals
--------------------------------
    Many different terminal types are described, like the Linux
    console, as being "VT100-compatible".  Here we discuss
    differences between the Linux console and the two most important
    others, the DEC VT102 and xterm(1).

    Control-character handling
    -------------------------- 

    The VT102 also recognized the following control characters:

    NUL (0x00)
           was ignored;

    ENQ (0x05)
           triggered an answerback message;

    DC1 (0x11, ^Q, XON)
           resumed transmission;

    DC3 (0x13, ^S, XOFF)
           caused VT100 to ignore (and stop transmitting) all codes
           except XOFF and XON.

    VT100-like DC1/DC3 processing may be enabled by the terminal driver.

    The xterm(1) program (in VT100 mode) recognizes the control
    characters BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.

---- snip ----

BUGS 
       In Linux 2.0.23, CSI is broken, and NUL is not ignored inside
       escape sequences.

       Some older kernel versions (after Linux 2.0) interpret 8-bit
       control sequences.  These "C1 controls" use codes between 128 and
       159 to replace ESC [, ESC ] and similar two-byte control sequence
       initiators (CSI).  There are fragments of that in modern kernels
       (either overlooked or broken by changes to support UTF-8), but
       the implementation is incomplete and should be regarded as
       unreliable.

       Linux "private mode" sequences do not follow the rules in ECMA-48
       for private mode control sequences.  In particular, those ending
       with ] do not use a standard terminating character.  The OSC (set
       palette) sequence is a greater problem, since xterm(1) may
       interpret this as a control sequence which requires a string
       terminator (ST).  Unlike the setterm(1) sequences which will be
       ignored (since they are invalid control sequences), the palette
       sequence will make xterm(1) appear to hang (though pressing the
       return-key will fix that).  To accommodate applications which
       have been hardcoded to use Linux control sequences, set the
       xterm(1) resource brokenLinuxOSC to true.

       An older version of this document implied that Linux recognizes
       the ECMA-48 control sequence for invisible text.  It is ignored.

  STTY(1)                 FreeBSD General Commands Manual                STTY(1)
  
  NAME
       stty – set the options for a terminal device interface
  
  SYNOPSIS
       stty [-a | -e | -g] [-f file] [arguments]
  
  DESCRIPTION
       The stty utility sets or reports on terminal characteristics for the
       device that is its standard input.  If no options or arguments are
       specified, it reports the settings of a subset of characteristics as well
       as additional ones if they differ from their default values.  Otherwise
       it modifies the terminal state according to the specified arguments.
       Some combinations of arguments are mutually exclusive on some terminal
       types.

---- snip ----

     Local Modes:
       Local mode flags (lflags) affect various and sundry characteristics of
       terminal processing.  Historically the term "local" pertained to new job
       control features implemented by Jim Kulp on a Pdp 11/70 at IIASA.  Later
       the driver ran on the first VAX at Evans Hall, UC Berkeley, where the job
       control details were greatly modified but the structure definitions and
       names remained essentially unchanged.  The second interpretation of the
       'l' in lflag is ``line discipline flag'' which corresponds to the c_lflag
       of the termios structure.
  
---- snip ----

       icanon (-icanon)
                   Enable (disable) canonical input (ERASE and KILL processing).
  
       iexten (-iexten)
                   Enable (disable) any implementation defined special control
                   characters not currently controlled by icanon, isig, or ixon.

---- snip ----
  
     Control Characters:
       control-character string
                   Set control-character to string.  If string is a single
                   character, the control character is set to that character.
                   If string is the two character sequence "^-" or the string
                   "undef" the control character is disabled (i.e., set to
                   {_POSIX_VDISABLE}.)
  
                   Recognized control-characters:
  
                         control-
                         character    Subscript    Description
                         _________    _________    _______________
                         eof          VEOF         EOF character
                         eol          VEOL         EOL character
                         eol2         VEOL2        EOL2 character
                         erase        VERASE       ERASE character
                         erase2       VERASE2      ERASE2 character
                         werase       VWERASE      WERASE character
                         intr         VINTR        INTR character
                         kill         VKILL        KILL character
                         quit         VQUIT        QUIT character
                         susp         VSUSP        SUSP character
                         start        VSTART       START character
                         stop         VSTOP        STOP character
                         dsusp        VDSUSP       DSUSP character
                         lnext        VLNEXT       LNEXT character
                         reprint      VREPRINT     REPRINT character
                         status       VSTATUS      STATUS character

---- snip ----

     Compatibility Modes:
       These modes remain for compatibility with the previous version of the
       stty command.

---- snip ----

       cbreak      If set, enables brkint, ixon, imaxbel, opost, isig, iexten,
                   and -icanon.  If unset, same as sane.

---- snip ----

hexdump -v -e '/1 " 0x%02x "' -e '/1 "%03o "' -e '/1 "%_u\n"'

$ uname -v
FreeBSD 12.0-RELEASE-p10 GENERIC 
 
$ ps $$
  PID TT  STAT    TIME COMMAND
64763  6  Ss   0:01.11 -tcsh (tcsh)
 
$ printf %s\\n "$SHELL"
/bin/tcsh
 
$ printf %s\\n "$TERM"
xterm-new

$ sysctl -d kern.console
kern.console: Console device control

$ sysctl kern.console
kern.console: ttyv0,/ttyv0,

$ freebsd-version
12.0-RELEASE-p10
 
$ uname -a
FreeBSD freebsd3.my.domain 12.0-RELEASE-p10 FreeBSD 12.0-RELEASE-p10 GENERIC  amd64
 
$ ps $$
  PID TT  STAT    TIME COMMAND
68481  0  Ss   0:01.15 -tcsh (tcsh)
 
$ printf %s\\n "$SHELL"
/bin/tcsh
 
$ printf %s\\n "$TERM"
xterm-new
 
$ printf %s\\n "$TERMCAP"
xterm-new|modern xterm:@7=\EOF:@8=\EOM:F1=\E[23~:F2=\E[24~:K2=\EOE:Km=\E[M:k1=\EOP:k2=\EOQ:k3=\EOR:k4=\EOS:k5=\E[15~:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:k;=\E[21~:kI=\E[2~:kN=\E[6~:kP=\E[5~:kd=\EOB:kh=\EOH:kl=\EOD:kr=\EOC:ku=\EOA:am:bs:km:mi:ms:ut:xn:AX:Co#8:co#142:kn#12:li#38:pa#64:AB=\E[4%dm:AF=\E[3%dm:AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:ae=\E(B:al=\E[L:as=\E(0:bl=^G:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:cm=\E[%i%d;%dH:cs=\E[%i%d;%dr:ct=\E[3g:dc=\E[P:dl=\E[M:ei=\E[4l:ho=\E[H:im=\E[4h:is=\E[!p\E[?3;4l\E[4l\E>:kD=\E[3~:ke=\E[?1l\E>:ks=\E[?1h\E=:kB=\E[Z:le=^H:md=\E[1m:me=\E[m:ml=\El:mr=\E[7m:mu=\Em:nd=\E[C:op=\E[39;49m:rc=\E8:rs=\E[!p\E[?3;4l\E[4l\E>:sc=\E7:se=\E[27m:sf=^J:so=\E[7m:sr=\EM:st=\EH:ue=\E[24m:up=\E[A:us=\E[4m:ve=\E[?12l\E[?25h:vi=\E[?25l:vs=\E[?12;25h:kb=\010:
 
$ stty -a
speed 38400 baud; 34 rows; 144 columns;
lflags: icanon isig iexten echo echoe echok echoke -echonl echoctl
        -echoprt -altwerase -noflsh -tostop -flusho -pendin -nokerninfo
        -extproc
iflags: -istrip icrnl -inlcr -igncr ixon -ixoff -ixany -imaxbel -ignbrk
        -brkint -inpck -ignpar -parmrk
oflags: opost onlcr -ocrnl tab3 -onocr -onlret
cflags: cread cs7 parenb -parodd hupcl -clocal -cstopb -crtscts -dsrflow
        -dtrflow -mdmbuf
cchars: discard = ^O; dsusp = ^Y; eof = ^D; eol = <undef>;
        eol2 = <undef>; erase = ^H; erase2 = ^H; intr = ^C; kill = ^U;
        lnext = ^V; min = 1; quit = ^\; reprint = ^R; start = ^Q;
        status = ^T; stop = ^S; susp = ^Z; time = 0; werase = ^W;

$ locate ttydefaults
/usr/include/sys/ttydefaults.h
/usr/local/lib/perl5/site_perl/mach/5.30/sys/ttydefaults.ph
/usr/src/sys/sys/ttydefaults.h
 
$ ls -lh /usr/include/sys/ttydefaults.h 
-r--r--r--  1 root  wheel   4.0K Jan  4  2019 /usr/include/sys/ttydefaults.h
 
$ ls -lh /usr/src/sys/sys/ttydefaults.h 
-rw-r--r--  1 root  wheel   4.0K Feb  9  2019 /usr/src/sys/sys/ttydefaults.h
 
$ diff /usr/src/sys/sys/ttydefaults.h /usr/include/sys/ttydefaults.h 
 
$ file /usr/include/sys/ttydefaults.h
/usr/include/sys/ttydefaults.h: C source, ASCII text
 
$ wc -l /usr/include/sys/ttydefaults.h
     113 /usr/include/sys/ttydefaults.h

$ cat /usr/include/sys/ttydefaults.h
/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)ttydefaults.h       8.4 (Berkeley) 1/21/94
 * $FreeBSD: releng/12.0/sys/sys/ttydefaults.h 326023 2017-11-20 19:43:44Z pfg $
 */

/*
 * System wide defaults for terminal state.
 */
#ifndef _SYS_TTYDEFAULTS_H_
#define _SYS_TTYDEFAULTS_H_

/*
 * Defaults on "first" open.
 */
#define TTYDEF_IFLAG    (BRKINT | ICRNL | IMAXBEL | IXON | IXANY)
#define TTYDEF_OFLAG    (OPOST | ONLCR)
#define TTYDEF_LFLAG_NOECHO (ICANON | ISIG | IEXTEN)
#define TTYDEF_LFLAG_ECHO (TTYDEF_LFLAG_NOECHO \
        | ECHO | ECHOE | ECHOKE | ECHOCTL)
#define TTYDEF_LFLAG TTYDEF_LFLAG_ECHO
#define TTYDEF_CFLAG    (CREAD | CS8 | HUPCL)
#define TTYDEF_SPEED    (B9600)

/*
 * Control Character Defaults
 */
/*
 * XXX: A lot of code uses lowercase characters, but control-character
 * conversion is actually only valid when applied to uppercase
 * characters. We just treat lowercase characters as if they were
 * inserted as uppercase.
 */
#define CTRL(x) ((x) >= 'a' && (x) <= 'z' ? \
        ((x) - 'a' + 1) : (((x) - 'A' + 1) & 0x7f))
#define CEOF            CTRL('D')
#define CEOL            0xff            /* XXX avoid _POSIX_VDISABLE */
#define CERASE          CTRL('?')
#define CERASE2         CTRL('H')
#define CINTR           CTRL('C')
#define CSTATUS         CTRL('T')
#define CKILL           CTRL('U')
#define CMIN            1
#define CQUIT           CTRL('\\')
#define CSUSP           CTRL('Z')
#define CTIME           0
#define CDSUSP          CTRL('Y')
#define CSTART          CTRL('Q')
#define CSTOP           CTRL('S')
#define CLNEXT          CTRL('V')
#define CDISCARD        CTRL('O')
#define CWERASE         CTRL('W')
#define CREPRINT        CTRL('R')
#define CEOT            CEOF
/* compat */
#define CBRK            CEOL
#define CRPRNT          CREPRINT
#define CFLUSH          CDISCARD

/* PROTECTED INCLUSION ENDS HERE */
#endif /* !_SYS_TTYDEFAULTS_H_ */

/*
 * #define TTYDEFCHARS to include an array of default control characters.
 */
#ifdef TTYDEFCHARS

#include <sys/cdefs.h>
#include <sys/_termios.h>

static const cc_t ttydefchars[] = {
        CEOF, CEOL, CEOL, CERASE, CWERASE, CKILL, CREPRINT, CERASE2, CINTR,
        CQUIT, CSUSP, CDSUSP, CSTART, CSTOP, CLNEXT, CDISCARD, CMIN, CTIME,
        CSTATUS, _POSIX_VDISABLE
};
_Static_assert(sizeof(ttydefchars) / sizeof(cc_t) == NCCS,
    "Size of ttydefchars does not match NCCS");

#undef TTYDEFCHARS
#endif /* TTYDEFCHARS */

$ sed -n l

$ hexdump -v -e '/1 " 0x%02x "' -e '/1 "%03o "' -e '/1 "%_u\n"' 
(It adds a lf when used on keyboard input though (i.e. not pipe from tput).) 

$ pkg info --regex showkey
showkey-1.7

$ tset -
xterm-new

$ infocmp -I -1 | grep -w ed
        ed=\E[J,
 
$  man terminfo

   The ed (string) capability in terminfo --> cd in termcap

$ infocmp -C -1 | grep -w cd
infocmp: xterm-new entry is 1123 bytes long
        :cd=\E[J:\

$ tput cd | od -c
0000000  033   [   J                                                    
0000003

$ tput clear

kill rings (buffers)
interrupt key
verbatim insert
key ID (KID)
C0 and C1 control codes
https://en.wikipedia.org/wiki/Keyboard_shortcut
control characters
caret notation
line discipline (LDISC) aka terminal I/O 

# ========================================================================= #
# XTerm Control Sequences from invisible-island.net as pythonic code.
# Basic control sequences are string variables.
#   - eg: ESC = '\033'
#         CSI = ESC + '['
# Control sequences that have args can be called to return a string.
#   - eg: sgr = CSI + Ps + 'm'
#         sgr(0) == '\033[0m' == sgr.RESET
# ========================================================================= #