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Copyright © 2014,2016 by Thomas E. Dickey

Table of function-keys for XTerm and other Terminal Emulators

In 2014, I noticed a comment, which relates to the PF1-PF4 assignment, but also to the use of function-key modifiers:

... four of the function keys that had been working fine in rxvt did not work in XTerm.

and referencing a table from 2005 on another site. Some of the discussion in the latter page was (is still) incorrect.
Here is a better table generated from the ncurses database, illustrating a few points:

• X11R6 xterm function keys did not send sequences such as ^[[20;2~. I started doing that in xterm with patch #94, in 1999.
• The unmodified function keys are available via a runtime menu.
  The corresponding terminal description is “xterm-vt220”
• The XFree86 xterm entry referred to was release 4.4, in 2004. That is a little old.
• I made some of the behavior configurable to move key-modifiers to the second parameter, and
  deprecate use of SS3 (the \EO string):
  • modifyCursorKeys in patch #167 and
  • modifyFunctionKeys in patch #216
• VTE (cited as "GNOME Terminal" in the discussion) uses the older—pre-216—behavior (sending SS3 for modified function keys), like Konsole.
• The developers of rxvt had no particular interest in providing PF1-PF4.
  While usable as an ANSI terminal, its keypad fell short of VMS's assumptions about VT100.
  Because the goals for rxvt and xterm differ, they are not necessarily compatible.

A few quirks deserve comment:

• Some entries have a kf0 capability. There is no standard about whether this is F0 or F10; the developers chose both.
• According to DEC documentation, VT220s do not really have F15 and F16.
  Those are the Help and Select keys. But I made my table show the codes labeled to match the other table.
• Some entries have Home and End keys (the "PC" convention) and others use the same escape sequences for Select and Remove (the "VT220" convention).
  See Why doesn't my keypad work? for more on that.
• Most of the extended keys are used for modified keys, e.g., using shift and/or control modifiers.
  See How can I use shift- or control-modifiers? for more on that.

This table gives a better example than that presented in Phillip Gold's page:

• Columns are named for the ncurses terminal entries, which are documented in the terminal database.
• The NAME column and capability data use terminfo syntax.
  The escape character is \E rather than the ambiguous ^[.
• The xterm-new entry in 2005 was the recommended one, and as long as shown in this table.
  Some details have changed (see patch #226 for example); this table is up to date.
  The last key is kf63, the last standard terminfo function key.
  While xterm defines more keys, there is also a 4096-byte limit on terminfo entries to consider.
  Both xterm and rxvt define more than the 35 function-keys in X's keysymdef.h file.
• All special keys are listed, including cursor-, keypad- and extended-keys.

This table was generated from ncurses' terminal database by

list_keys -tx \
        vt100 vt220 scoansi \
        xterm-r5 xterm-r6 xterm-vt220 xterm-xf86-v44 xterm-new \
        rxvt mgt screen

before tidying up the layout. The table is divided into four parts, listed alphabetically (except for function-keys):

1. cursor-keys
2. function-keys
3. special keys such as editing-keypad
4. extended (nonstandard) keys