








			Xterm Control Sequences

			       Edward Moy
		   University of California, Berkeley

			       Revised by

			     Stephen Gildea
			  X Consortium (1994)

			     Thomas Dickey
			 XFree86 Project (1996)




Definitions

c    The literal character c.

C    A single (required) character.

Ps   A single (usually optional) numeric parameter, composed of one of
     more digits.

Pm   A multiple numeric parameter composed of any number of single
     numeric parameters, separated by ;  character(s).

Pt   A text parameter composed of printable characters.

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:

ESC D
     Index (IND: 0x84)
ESC E
     Next Line (NEL: 0x85)
ESC H
     Tab Set (HTS: 0x88)
ESC M
     Reverse Index (RI: 0x8d)
ESC N
     Single Shift Select of G2 Character Set (SS2: 0x8e): affects next
     character only
ESC O
     Single Shift Select of G3 Character Set (SS3: 0x8f): affects next
     character only
ESC P
     Device Control String (DCS: 0x90)
ESC V
     Start of Guarded Area (SPA: 0x96)
ESC W
     End of Guarded Area (EPA: 0x97)
ESC X
     Start of String (SOS: 0x98)
ESC Z
     Return Terminal ID (DECID: 0x9a).	Obsolete form of CSI c	(DA).
ESC [
     Control Sequence Introducer (CSI: 0x9b)
ESC \
     String Terminator (ST: 0x9c)
ESC ]
     Operating System Command (OSC: 0x9d)
ESC ^
     Privacy Message (PM: 0x9e)
ESC _
     Application Program Command (APC: 0x9f)

These control characters are used in the vtXXX emulation.

VT100 Mode
Most of these control sequences are standard VT102 control sequences,
but there is support for later DEC VT terminals (i.e., VT220 and VT320),
as well as ISO 6429 and aixterm color controls.  VT102 features not sup-
ported are double size characters and blinking characters.  There are
additional control sequences to provide xterm-dependent functions, such
as the scrollbar or window size.  Where the function is specified by DEC
or ISO 6429, the code assigned to it is given in parentheses.  The
escape codes to designate and invoke character sets are specified by ISO
2022; see that document for a discussion of character sets.

BEL	       Bell (Ctrl-G)
BS	       Backspace (Ctrl-H)
CR	       Carriage Return (Ctrl-M)
ENQ	       Return Terminal Status (Ctrl-E).  Response is the termi-
	       nal name, e.g., "xterm".
FF	       Form Feed or New Page (NP) (Ctrl-L) same as LF
LF	       Line Feed or New Line (NL) (Ctrl-J)
SO	       Shift Out (Ctrl-N) -> Switch to Alternate Character Set:
	       invokes the G1 character set.
SP	       Space.
TAB	       Horizontal Tab (HT) (Ctrl-I)
VT	       Vertical Tab (Ctrl-K) same as LF
SI	       Shift In (Ctrl-O) -> Switch to Standard Character Set:
	       invokes the G0 character set (the default).

ESC SP F       7-bit controls (S7C1T).
ESC SP G       8-bit controls (S8C1T).
ESC SP L       Set ANSI conformance level 1 (vt100, 7-bit controls).
ESC SP M       Set ANSI conformance level 2 (vt200).
ESC SP N       Set ANSI conformance level 3 (vt300).
ESC # 8        DEC Screen Alignment Test (DECALN)
ESC ( C        Designate G0 Character Set (ISO 2022)
		 C = 0	-> DEC Special Character and Line Drawing Set
		 C = A	-> United Kingdom (UK)
		 C = B	-> United States (USASCII)
ESC ) C        Designate G1 Character Set (ISO 2022)
		 C = 0	-> DEC Special Character and Line Drawing Set
		 C = A	-> United Kingdom (UK)
		 C = B	-> United States (USASCII)
ESC * C        Designate G2 Character Set (ISO 2022)
		 C = 0	-> DEC Special Character and Line Drawing Set
		 C = A	-> United Kingdom (UK)
		 C = B	-> United States (USASCII)
ESC + C        Designate G3 Character Set (ISO 2022)
		 C = 0	-> DEC Special Character and Line Drawing Set
		 C = A	-> United Kingdom (UK)
		 C = B	-> United States (USASCII)
ESC 7	       Save Cursor (DECSC)
ESC 8	       Restore Cursor (DECRC)
ESC =	       Application Keypad (DECPAM)
ESC >	       Normal Keypad (DECPNM)
ESC F	       Cursor to lower left corner of screen (if enabled by the
	       hpLowerleftBugCompat resource).
ESC c	       Full Reset (RIS)
ESC l	       Memory Lock (per HP terminals).	Locks memory above the
	       cursor.
ESC m	       Memory Unlock (per HP terminals)
ESC n	       Invoke the G2 Character Set (LS2)
ESC o	       Invoke the G3 Character Set (LS3)
ESC |	       Invoke the G3 Character Set as GR (LS3R).  Has no visible
	       effect in xterm.
ESC }	       Invoke the G2 Character Set as GR (LS2R).  Has no visible
	       effect in xterm.
ESC ~	       Invoke the G1 Character Set as GR (LS1R).  Has no visible
	       effect in xterm.

APC Pt ST      xterm implements no APC functions; Pt is ignored.  Pt
	       need not be printable characters.

DCS Ps; Ps| Pt ST
	       User-Defined Keys (DECUDK).  The first parameter:
		 Ps = 0  -> Clear all UDK definitions before starting
	       (default)
		 Ps = 1  -> Erase Below (default)
	       The second parameter:
		 Ps = 0  -> Lock the keys (default)
		 Ps = 1  -> Do not lock.
	       The third parameter is a ';'-separated list of strings
	       denoting the key-code separated by a '/' from the hex-
	       encoded key value.  The key codes correspond to the DEC
	       function-key codes (e.g., F6=17).
DCS $ q Pt ST  Request Status String (DECRQSS).  The string following
	       the "q" is one of the following:
		 " q	 -> DECSCA
		 " p	 -> DECSCL
		 r	 -> DECSTBM
		 m	 -> SGR
	       xterm responds with DCS 1 $ r Pt ST for valid requests,
	       replacing the Pt with the corresponding CSI string, or
	       DCS 0 $ r Pt ST for invalid requests.

CSI Ps @       Insert Ps (Blank) Character(s) (default = 1) (ICH)
CSI Ps A       Cursor Up Ps Times (default = 1) (CUU)
CSI Ps B       Cursor Down Ps Times (default = 1) (CUD)
CSI Ps C       Cursor Forward Ps Times (default = 1) (CUF)
CSI Ps D       Cursor Backward Ps Times (default = 1) (CUB)
CSI Ps E       Cursor Next Line Ps Times (default = 1) (CNL)
CSI Ps F       Cursor Preceding Line Ps Times (default = 1) (CPL)
CSI Ps G       Cursor Character Absolute  [column] (default = [row,1])
	       (CHA)
CSI Ps ; Ps H  Cursor Position [row;column] (default = [1,1]) (CUP)
CSI Ps I       Cursor Forward Tabulation Ps tab stops (default = 1)
	       (CHT)
CSI Ps J       Erase in Display (ED)
		 Ps = 0  -> Erase Below (default)
		 Ps = 1  -> Erase Above
		 Ps = 2  -> Erase All
CSI Ps ?  J    Erase in Display (DECSED)
		 Ps = 0  -> Selective Erase Below (default)
		 Ps = 1  -> Selective Erase Above
		 Ps = 2  -> Selective Erase All
CSI Ps K       Erase in Line (EL)
		 Ps = 0  -> Erase to Right (default)
		 Ps = 1  -> Erase to Left
		 Ps = 2  -> Erase All
CSI Ps ?  K    Erase in Line (DECSEL)
		 Ps = 0  -> Selective Erase to Right (default)
		 Ps = 1  -> Selective Erase to Left
		 Ps = 2  -> Selective Erase All
CSI Ps L       Insert Ps Line(s) (default = 1) (IL)
CSI Ps M       Delete Ps Line(s) (default = 1) (DL)
CSI Ps P       Delete Ps Character(s) (default = 1) (DCH)
CSI Ps S       Scroll up Ps lines (default = 1) (SU)
CSI Ps T       Scroll down Ps lines (default = 1) (SD, according to DEC)
CSI Ps ; Ps ; Ps ; Ps ; Ps T
	       Initiate hilite mouse tracking.	Parameters are
	       [func;startx;starty;firstrow;lastrow].  See the section
	       Mouse Tracking.
CSI Ps X       Erase Ps Character(s) (default = 1) (ECH)
CSI Ps Z       Cursor Backward Tabulation Ps tab stops (default = 1)
	       (CBT)
CSI Ps ^       Scroll down Ps lines (default = 1) (SD, according to ISO)
CSI Pm `       Character Position Absolute  [column] (default = [row,1])
	       (HPA)
CSI Ps b       Repeat the preceding graphic character Ps times (REP)
CSI Ps c       Send Device Attributes (DA)
		 Ps = 0  or omitted -> request attributes from terminal
		 -> CSI ? 1 ; 2 c  (``I am a VT100 with Advanced Video
	       Option.'')
CSI Pm d       Line Position Absolute  [row] (default = [1,column])
	       (VPA)
CSI Ps ; Ps f  Horizontal and Vertical Position [row;column] (default =
	       [1,1]) (HVP)
CSI Ps g       Tab Clear (TBC)
		 Ps = 0  -> Clear Current Column (default)
		 Ps = 3  -> Clear All
CSI Pm h       Set Mode (SM)
		 Ps = 4  -> Insert Mode (IRM)
		 Ps = 2 0  -> Automatic Newline (LNM)
CSI Pm l       Reset Mode (RM)
		 Ps = 4  -> Replace Mode (IRM)
		 Ps = 2 0  -> Normal Linefeed (LNM)
CSI Pm m       Character Attributes (SGR)
		 Ps = 0  -> Normal (default)
		 Ps = 1  -> Bold
		 Ps = 4  -> Underlined
		 Ps = 5  -> Blink (appears as Bold)
		 Ps = 7  -> Inverse
		 Ps = 2 2  -> Normal (neither bold nor faint)
		 Ps = 2 4  -> Not underlined
		 Ps = 2 5  -> Steady (not blinking)
		 Ps = 2 7  -> Positive (not inverse)
		 Ps = 3 0  -> Set foreground color to Black
		 Ps = 3 1  -> Set foreground color to Red
		 Ps = 3 2  -> Set foreground color to Green
		 Ps = 3 3  -> Set foreground color to Yellow
		 Ps = 3 4  -> Set foreground color to Blue
		 Ps = 3 5  -> Set foreground color to Magenta
		 Ps = 3 7  -> Set foreground color to Cyan
		 Ps = 3 7  -> Set foreground color to White
		 Ps = 3 9  -> Set foreground color to default (original)
		 Ps = 4 0  -> Set background color to Black
		 Ps = 4 1  -> Set background color to Red
		 Ps = 4 2  -> Set background color to Green
		 Ps = 4 3  -> Set background color to Yellow
		 Ps = 4 4  -> Set background color to Blue
		 Ps = 4 5  -> Set background color to Magenta
		 Ps = 4 6  -> Set background color to Cyan
		 Ps = 4 7  -> Set background color to White
		 Ps = 4 9  -> Set background color to default (origi-
	       nal).

	       If 16-color support is compiled, the following apply.
	       Assume that xterm's resources are set so that the ISO
	       color codes are the first 8 of a set of 16.  Then the
	       aixterm colors are the bright versions of the ISO colors:
		 Ps = 9 0  -> Set foreground color to Black
		 Ps = 9 1  -> Set foreground color to Red
		 Ps = 9 2  -> Set foreground color to Green
		 Ps = 9 3  -> Set foreground color to Yellow
		 Ps = 9 4  -> Set foreground color to Blue
		 Ps = 9 5  -> Set foreground color to Magenta
		 Ps = 9 7  -> Set foreground color to Cyan
		 Ps = 9 7  -> Set foreground color to White
		 Ps = 1 0 0  -> Set background color to Black
		 Ps = 1 0 1  -> Set background color to Red
		 Ps = 1 0 2  -> Set background color to Green
		 Ps = 1 0 3  -> Set background color to Yellow
		 Ps = 1 0 4  -> Set background color to Blue
		 Ps = 1 0 5  -> Set background color to Magenta
		 Ps = 1 0 6  -> Set background color to Cyan
		 Ps = 1 0 7  -> Set background color to White

	       If xterm is compiled with the 16-color support disabled,
	       it supports the following, from rxvt:
		 Ps = 1 0 0  -> Set foreground and background color to
	       default

CSI Ps n       Device Status Report (DSR)
		 Ps = 5  -> Status Report CSI 0 n  (``OK'')
		 Ps = 6  -> Report Cursor Position (CPR) [row;column] as
	       CSI r ; c R
CSI Ps ? n     Device Status Report (DSR, DEC-specific)
		 Ps = 6  -> Report Cursor Position (CPR) [row;column] as
	       CSI ? r ; c R (assumes page is zero).
		 Ps = 1 5  -> Report Printer status as CSI ? 1 0  n
	       (ready) or CSI ? 1 1  n	(not ready)
		 Ps = 2 5  -> Report UDK status as CSI ? 2 0  n
	       (unlocked) or CSI ? 2 1	n  (locked)
		 Ps = 2 6  -> Report Keyboard status as CSI ? 2 7  ;  1
	       ;  0  ;	0  n  (North American)
CSI  ! p       Soft terminal reset (DECSTR)
CSI Ps ; Ps " p
	       Set conformance level (DECSCL) Valid values for the first
	       parameter:
		 Ps = 6 1  -> VT100
		 Ps = 6 2  -> VT200
		 Ps = 6 3  -> VT300 Valid values for the second parame-
	       ter:
		 Ps = 0  -> 8-bit controls
		 Ps = 1  -> 7-bit controls (always set for VT100)
		 Ps = 2  -> 8-bit controls
CSI Ps " q     Select character protection attribute (DECSCA).	Valid
	       values for the parameter:
		 Ps = 0  -> DECSED and DECSEL can erase (default)
		 Ps = 1  -> DECSED and DECSEL cannot erase
		 Ps = 2  -> DECSED and DECSEL can erase
CSI Ps ; Ps r  Set Scrolling Region [top;bottom] (default = full size of
	       window) (DECSTBM)
CSI Ps ;  Ps ; Ps t
	       Window manipulation (from dtterm).  Valid values for the
	       first (and any additional parameters) are:
		 Ps = 1  -> Restore (de-iconify) window.
		 Ps = 2  -> Minimize (iconify) window.
		 Ps = 3  ; x ; y -> Move window to [x, y].
		 Ps = 4  ; height ; width -> Resize the xterm window to
	       height and width in pixels.
		 Ps = 5  -> Raise the xterm window to the front of the
	       stacking order.
		 Ps = 6  -> Lower the xterm window to the bottom of the
	       stacking order.
		 Ps = 7  -> Refresh the xterm window.
		 Ps = 8  ; height ; width -> Resize the text area to
	       [height;width] in characters.
		 Ps = 1 1  -> Report xterm window state.  If the xterm
	       window is open (non-iconified), it returns CSI 1 t .  If
	       the xterm window is iconified, it returns CSI 2 t .
		 Ps = 1 3  -> Report xterm window position as CSI 3 ; x;
	       yt
		 Ps = 1 4  -> Report xterm window in pixels as CSI  4  ;
	       height ;  width t
		 Ps = 1 8  -> Report the size of the text area in char-
	       acters as CSI  8  ;  height ;  widtht
		 Ps = 2 0  -> Report xterm window's icon label as OSC  L
	       label ST
		 Ps = 2 1  -> Report xterm window's title as OSC  l
	       title ST
		 Ps >= 2 4  -> Resize to Ps lines (DECSLPP)
CSI Ps x       Request Terminal Parameters (DECREQTPARM)
CSI ? Pm h     DEC Private Mode Set (DECSET)
		 Ps = 1  -> Application Cursor Keys (DECCKM)
		 Ps = 2  -> Designate USASCII for character sets G0-G3
	       (DECANM), and set VT100 mode.
		 Ps = 3  -> 132 Column Mode (DECCOLM)
		 Ps = 4  -> Smooth (Slow) Scroll (DECSCLM)
		 Ps = 5  -> Reverse Video (DECSCNM)
		 Ps = 6  -> Origin Mode (DECOM)
		 Ps = 7  -> Wraparound Mode (DECAWM)
		 Ps = 8  -> Auto-repeat Keys (DECARM)
		 Ps = 9  -> Send Mouse X & Y on button press.  See the
	       section Mouse Tracking.
		 Ps = 2 5  -> Show Cursor (DECTCEM)
		 Ps = 3 8  -> Enter Tektronix Mode (DECTEK)
		 Ps = 4 0  -> Allow 80 -> 132 Mode
		 Ps = 4 1  -> more(1) fix (see curses resource)
		 Ps = 4 4  -> Turn On Margin Bell
		 Ps = 4 5  -> Reverse-wraparound Mode
		 Ps = 4 6  -> Start Logging (normally disabled by a com-
	       pile-time option)
		 Ps = 4 7  -> Use Alternate Screen Buffer (unless dis-
	       abled by the titeInhibit resource)
		 Ps = 1 0 0 0  -> Send Mouse X & Y on button press and
	       release.  See the section Mouse Tracking.
		 Ps = 1 0 0 1  -> Use Hilite Mouse Tracking.  See the
	       section Mouse Tracking.
CSI ? Pm l     DEC Private Mode Reset (DECRST)
		 Ps = 1  -> Normal Cursor Keys (DECCKM)
		 Ps = 2  -> Designate VT52 mode (DECANM).
		 Ps = 3  -> 80 Column Mode (DECCOLM)
		 Ps = 4  -> Jump (Fast) Scroll (DECSCLM)
		 Ps = 5  -> Normal Video (DECSCNM)
		 Ps = 6  -> Normal Cursor Mode (DECOM)
		 Ps = 7  -> No Wraparound Mode (DECAWM)
		 Ps = 8  -> No Auto-repeat Keys (DECARM)
		 Ps = 9  -> Don't Send Mouse X & Y on button press
		 Ps = 2 5  -> Hide Cursor (DECTCEM)
		 Ps = 4 0  -> Disallow 80 -> 132 Mode
		 Ps = 4 1  -> No more(1) fix (see curses resource)
		 Ps = 4 4  -> Turn Off Margin Bell
		 Ps = 4 5  -> No Reverse-wraparound Mode
		 Ps = 4 6  -> Stop Logging (normally disabled by a com-
	       pile-time option)
		 Ps = 4 7  -> Use Normal Screen Buffer
		 Ps = 1 0 0 0  -> Don't Send Mouse X & Y on button press
	       and release
		 Ps = 1 0 0 1  -> Don't Use Hilite Mouse Tracking
CSI ? Pm r     Restore DEC Private Mode Values.  The value of Ps previ-
	       ously saved is restored.  Ps values are the same as for
	       DECSET.
CSI ? Pm s     Save DEC Private Mode Values.  Ps values are the same as
	       for DECSET.

OSC Ps ; Pt ST
OSC Ps ; Pt BEL
	       Set Text Parameters
		 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 = 1 0  -> Change color names starting with text
	       foreground to Pt (a list of one or more color names, sep-
	       arated by semicolon, up to color6).
		 Ps = 1 1  -> Change colors starting with text back-
	       ground to Pt
		 Ps = 1 2  -> Change colors starting with text cursor to
	       Pt
		 Ps = 1 3  -> Change colors starting with mouse fore-
	       ground to Pt
		 Ps = 1 4  -> Change colors starting with mouse back-
	       ground to Pt
		 Ps = 1 5  -> Change colors starting with Tek foreground
	       to Pt
		 Ps = 1 6  -> Change colors starting with Tek background
	       to Pt
		 Ps = 4 6  -> Change Log File to Pt (normally disabled
	       by a compile-time option)
		 Ps = 5 0  -> Set Font to Pt

PM Pt ST       xterm implements no PM functions; Pt is ignored.  Pt need
	       not be printable characters.

Mouse Tracking
The VT widget can be set to send the mouse position and other informa-
tion on button presses.  These modes are typically used by editors and
other full-screen applications that want to make use of the mouse.
There are three mutually exclusive modes, each enabled (or disabled) by
a different parameter in the DECSET (or DECRST) escape sequence.  Param-
eters for all mouse tracking escape sequences generated by xterm encode
numeric parameters in a single character as value+040.	For example, !
is 1.  The screen coodinate system is 1-based.
X10 compatibility mode sends an escape sequence on button press encoding
the location and the mouse button pressed.  It is enabled by specifying
parameter 9 to DECSET.	On button press, xterm sends CSI M CbCxCy (6
characters).  Cb is button-1.  Cx and Cy are the x and y coordinates of
the mouse when the button was pressed.
Normal tracking mode sends an escape sequence on both button press and
release.  Modifier information is also sent.  It is enabled by specify-
ing parameter 1000 to DECSET.  On button press or release, xterm sends
CSI M CbCxCy.  The low two bits of Cb encode button information: 0=MB1
pressed, 1=MB2 pressed, 2=MB3 pressed, 3=release.  The upper bits encode
what modifiers were down when the button was pressed and are added
together.  4=Shift, 8=Meta, 16=Control.  Cx and Cy are the x and y coor-
dinates of the mouse event.  The upper left corner is (1,1).
Mouse hilite tracking notifies a program of a button press, receives a
range of lines from the program, highlights the region covered by the
mouse within that range until button release, and then sends the program
the release coordinates.  It is enabled by specifying parameter 1001 to
DECSET.  Highlighting is performed only for button 1, though other but-
ton events can be received.  Warning: use of this mode requires a coop-
erating program or it will hang xterm.	On button press, the same infor-
mation as for normal tracking is generated; xterm then waits for the
program to send mouse tracking information.  All X events are ignored
until the proper escape sequence is received from the pty: CSI Ps ; Ps ;
Ps ; Ps ; Ps T .  The parameters are func, startx, starty, firstrow, and
lastrow.  func is non-zero to initiate hilite tracking and zero to
abort.	startx and starty give the starting x and y location for the
highlighted region.  The ending location tracks the mouse, but will
never be above row firstrow and will always be above row lastrow.  (The
top of the screen is row 1.)  When the button is released, xterm reports
the ending position one of two ways: if the start and end coordinates
are valid text locations: CSI t CxCy.  If either coordinate is past the
end of the line: CSI T CxCyCxCyCxCy.  The parameters are startx, starty,
endx, endy, mousex, and mousey.  startx, starty, endx, and endy give the
starting and ending character positions of the region.	mousex and
mousey give the location of the mouse at button up, which may not be
over a character.

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.

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 (ignored by xterm) (ESC Ctrl-N)
ESC SI	       End 4015 APL mode (ignored by xterm) (ESC Ctrl-O)
ESC ETB        COPY (Save Tektronix Codes to file COPYyyyy-mm-
	       dd.hh:mm:ss) (ESC 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 (normally disabled
	       by a compile-time option)
ESC `	       Normal Z Axis and Normal (solid) Vectors
ESC a	       Normal Z Axis and Dotted Line Vectors
ESC b	       Normal Z Axis and Dot-Dashed Vectors
ESC c	       Normal Z Axis and Short-Dashed Vectors
ESC d	       Normal Z Axis and Long-Dashed Vectors
ESC h	       Defocused Z Axis and Normal (solid) Vectors
ESC i	       Defocused Z Axis and Dotted Line Vectors
ESC j	       Defocused Z Axis and Dot-Dashed Vectors
ESC k	       Defocused Z Axis and Short-Dashed Vectors
ESC l	       Defocused Z Axis and Long-Dashed Vectors
ESC p	       Write-Thru Mode and Normal (solid) Vectors
ESC q	       Write-Thru Mode and Dotted Line Vectors
ESC r	       Write-Thru Mode and Dot-Dashed Vectors
ESC s	       Write-Thru Mode and Short-Dashed Vectors
ESC t	       Write-Thru Mode and Long-Dashed Vectors
FS	       Point Plot Mode (Ctrl-\)
GS	       Graph Mode (Ctrl-])
RS	       Incremental Plot Mode (Ctrl-^)
US	       Alpha Mode (Ctrl-_)

VT52 Mode
Parameters for cursor movement are at the end of the ESC Y  escape
sequence.  Each ordinate is encoded in a single character as value+040.
For example, !	is 1.  The screen coodinate system is 0-based.

ESC A	       Cursor up.
ESC B	       Cursor down.
ESC C	       Cursor right.
ESC D	       Cursor left.
ESC F	       Enter graphics mode.
ESC G	       Exit graphics mode.
ESC H	       Move the cursor to the home position.
ESC I	       Reverse line feed.
ESC J	       Erase from the cursor to the end of the screen.
ESC K	       Erase from the cursor to the end of the line.
ESC Y Ps Ps    Move the cursor to given row and column.
ESC Z	       Identify
		 -> ESC  /  Z  (``I am a VT52.'')
ESC =	       Enter alternate keypad mode.
ESC >	       Exit alternate keypad mode.
ESC <	       Exit VT52 mode (Enter VT100 mode).
