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$Id: user_caps.5,v 1.60 2025/11/12 01:01:01 tom Exp $
@TIC@ -x
Issue 4, Version 2 (1996). That list is not in man page format in
the standard, so lacks a "HISTORY" section. However, `tigetstr()`
and `tputs()` are identified in the same document as new to Issue 4,
so GBR conjectures that the list came in at the same time.
TED: the list is reflected in term.h, seen in examples from AIX 3 and 4,
HP-UX 9, OSF/1, Solaris 2.4, dating from 1992-1994 -- all before 1996.
The AIX 4 file has copyright dates starting in 1984;
the Solaris file cites 1988 (the others have no copyright comments).
Those term.h files note in a comment that it is generated by a script with
a data file, i.e.,
term.h - this file is automatically made from caps and maketerm.ex.
illumos-gate has related source, with a "caps" file having AT&T copyright
for 1988, and UCB copyright for 1982, 1986, 1988. That 1982 is interesting
(hinting that something may have been in the initial releases of System V)
but the first release with tic appears to be SVr2 in 1984.
Most such additions to this fixed repertoire suppelmented the tables of Boolean, numeric, and string capabilities. Rather than changing the meaning of an existing capability, a new name was added. The \%term\%info database uses a binary format; binary compatibility was ensured by using a header that counted the number of items in the tables for each type of capability. Because each curses vendor extended the standard capability lists in distinct ways, a library could be programmed to recognize only compiled \%term\%info entries that it was prepared to interpret. Standardization was incomplete. .bP X/Open Curses describes only the source format, not its binary representation on disk.
Library developers rely upon SVr4 documentation and reverse engineering of compiled \%term\%info files to match the binary format. .bP Lacking a standard for the binary format, most implementations copy the SVr2 binary format, which uses 16-bit signed integers, and is limited to 4096-byte entries. The SVr2 format cannot represent very large numeric capability values, nor can it represent large numbers of key definitions, as are required to distinguish multiple modifier keys used in combination with a function key. .bP The tables of capability names differ between implementations. Although they may provide all of the standard capability names, each arranges its table entries differently because some features were added as needed, while others were added \(em out of order \(em for X/Open Curses conformance. While ncurses 's capability repertoire is closest to that of Solaris, the set of capabilities supported by each vendor's \%term\%info database differs from the list published by X/Open Curses. \%ncurses can be configured with tables that match the terminal databases for AIX, HP-UX, or OSF/1, rather than the default Solaris-like configuration. .bP In SVr4 curses and \%ncurses "," the terminal database is defined at compile time by interpolating a text file that lists the different terminal capabilities. In principle, the text file can be extended, but doing so requires recompiling and reinstalling the library. The text file used by \%ncurses for terminal capabilities includes details of extensions to X/Open Curses made by various systems. For example, \%ncurses supports the following nonstandard capabilities in each configuration.
5 memory_lock ( meml ) lock memory above cursor
5 memory_unlock ( memu ) unlock memory
5 box_chars_1 ( box1 ) box characters primary set
During the 1990s, some application developers were reluctant to use \%term\%info in spite of its performance (and other) advantages over termcap "." .bP The fixed repertoire prevented users from adding support for terminal features unanticipated by X/Open Curses (or required them to reuse existing capabilities as a workaround). .bP The limitation to 16-bit signed integers was also mentioned. Because termcap stores everything as a string, it could represent larger numbers.
Although termcap 's extensibility was rarely used \(em the claimant was never an implementor who had actually exercised it \(em the criticism had a point. \%ncurses 5.0 provided a way to detect nonstandard capabilities, to determine their type, and to optionally store and retrieve them in a way that did not interfere with other applications. ncurses terms these "user-defined capabilities" because no modifications to the standard capability list are needed.
The \%ncurses utilities \%@TIC@ and \%@INFOCMP@ have a command-line option \*(``-x\*('' to control whether the nonstandard capabilities are stored or retrieved. \%ncurses provides use_extended_names(3X) to programs for the same purpose.
When compiling a terminal database, if \*(``-x\*('' is used, \%@TIC@ stores a user-defined capability if the capability name is not standard.
Because \%ncurses provides a termcap library interface, these user-defined capabilities may be visible to termcap applications. .bP The termcap interface (like all implementations of termcap ) restricts capability names to two characters.
When the capability is simple enough for use in a termcap application, it is provided as a two-character name. .bP Other user-defined capabilities employ features not usable in termcap "," such as parameterized strings that use more than two parameters or require more powerful expressions than termcap supports. Such capabilities should, in the \%term\%info database, have names at least three characters in length. .bP Some terminals can send distinct strings for special keys (cursor-, keypad- or function-keys) depending on modifier keys (shift, control, etc.). While \%term\%info and termcap define a set of sixty function key names, to which a series of keys can be assigned, that is insufficient for more than a dozen keys multiplied by more than a couple of modifier combinations. The \%ncurses database uses a convention based on xterm(1) to provide extended special-key names. Fitting that into termcap 's limitation of 2-character names would be pointless. These extended keys are available only with \%term\%info "."
3 AX (Boolean) asserts that the terminal interprets SGR 39 and SGR 49 by resetting the foreground and background colors, respectively, to the default.
screen(1) recognizes this capability as well.3 E3 (string) tells an application how to clear the terminal's scrollback buffer. When present, the clear(1) program sends this before clearing the terminal.
The command \*(`` "tput clear" \*('' does the same thing.3 NQ (Boolean) suppresses a consistency check in \%@TIC@ for the \%ncurses string capabilities user6 ( u6 ) through user9 ( u9 ), which tell an application how to query the terminal's cursor position and its device attributes.
3 RGB (Boolean, numeric, or string) asserts that the \%set_a_foreground ( setaf ) and \%set_a_background ( setab ) capabilities employ "direct colors" "," using an RGB (red/green/blue) convention. This capability allows color_content(3X) to return appropriate values without requiring the application to initialize colors using init_color(3X).
The capability type determines the values \%ncurses sees.
3 Boolean implies that the number of bits for red, green, and blue are the same. Starting with the value of the capability max_colors \%( colors ; termcap: co ), \%ncurses adds two, divides the sum by three, and assigns the result to red, green, and blue, in that order.
If the number of bits needed for the number of colors is not a multiple of three, the blue (and green) color channels lose in comparison to red.3 numeric tells \%ncurses what result to add to red, green, and blue. If \%ncurses runs out of bits, blue (and green) lose just as in the Boolean case.
3 string specify the quantity of bits used for red, green, and blue color channels as a slash-separated list of decimal integers.
3 U8 (numeric) asserts whether \%ncurses must use Unicode values for line-drawing characters, and that it should ignore the alternate character set (ACS) capabilities when the locale uses UTF-8 encoding. See the discussion of \%NCURSES_NO_UTF8_ACS in section \*(``ENVIRONMENT\*('' of \%ncurses(3X).
Set this capability to a nonzero value to enable it.3 XM (string) override \%ncurses 's built-in string that directs xterm(1) to enable or disable mouse mode.
\%ncurses sends a character sequence to the terminal to initialize mouse mode, and when the user clicks the mouse buttons or (in certain modes) moves the mouse, handles the characters sent back by the terminal to tell the application what was done with the mouse. The mouse protocol is enabled when the mask argument to the mousemask(3X) function is nonzero. By default, \%ncurses handles the responses for the X11 xterm mouse protocol. It also knows about the SGR 1006 xterm mouse protocol, but must to be told to look for it specifically. \%ncurses is not be able to guess which of the two modes is used, because the responses are enough alike that only confusion would result. The XM capability has a single numeric parameter. If nonzero, the mouse protocol should be enabled. If zero, the mouse protocol should be disabled. \%ncurses inspects this capability if it is present, to see whether the 1006 protocol is used. If so, it expects the responses to use the SGR 1006 xterm mouse protocol. The xterm mouse protocol is used by other terminal emulators. The terminal database uses building blocks for the various xterm mouse protocols usable in customized terminal descriptions. The terminal database building blocks for this mouse feature also have an experimental capability, xm "," that describes the mouse response. No known interpreter uses this information, which could make mouse support completely data-driven. xm shows the format of the mouse responses. In this experimental capability, the parameters are as follows.
5 p1 y-ordinate
5 p2 x-ordinate
5 p3 button
5 p4 state, e.g., pressed or released
5 p5 y-ordinate starting region
5 p6 x-ordinate starting region
5 p7 y-ordinate ending region
5 p8 x-ordinate ending region
xterm+x11mouse|X11 xterm mouse protocol,
kmous=\eE[M, XM=\eE[?1000%?%p1%{1}%=%th%el%;,
xm=\eE[M
%?%p4%t%p3%e%{3}%;%' '%+%c
%p2%'!'%+%c
%p1%'!'%+%c,
xterm+sm+1006|xterm SGR-mouse,
kmous=\eE[<, XM=\eE[?1006;1000%?%p1%{1}%=%th%el%;,
xm=\eE[<%i%p3%d;
%p1%d;
%p2%d;
%?%p4%tM%em%;,
.
Since 1999, xterm(1) has supported shift, control, alt, and meta modifiers which produce distinct special-key strings. In a terminal description, \%ncurses has no special knowledge of the modifiers used. Applications can use the naming convention established for xterm to find these special keys in the terminal description.
Starting with the curses convention that capability codes describing the input generated by a terminal's key caps begin with \*(``k\*('', and that shifted special keys use uppercase letters in their names, \%ncurses 's terminal database defines the following names and codes to which a suffix is added.
| Code Description |
| kDC shifted kdch1 (delete character) |
| .\" kDC is a standard capability; see X/Open Curses Issue 7, p. 345. |
| kDN shifted kcud1 (cursor down) |
| kEND shifted kend (end) |
| kHOM shifted khome (home) |
| kLFT shifted kcub1 (cursor back) |
| kNXT shifted knext (next) |
| kPRV shifted kprev (previous) |
| kRIT shifted kcuf1 (cursor forward) |
| kUP shifted kcuu1 (cursor up) |
Keycap nomenclature on the Unix systems for which curses was developed differs from today's ubiquitous descendants of the IBM PC/AT keyboard layout. In the foregoing, interpret \*(``backward\*('' as \*(``left\*('', \*(``forward\*('' as \*(``right\*('', \*(``next\*('' as \*(``page down\*('', and \*(``prev(ious)\*('' as \*(``page up\*(''.
These are the suffixes used to denote the modifiers:
| Value/Description |
| 2/Shift |
| 3/Alt |
| 4/Shift + Alt |
| 5/Control |
| 6/Shift + Control |
| 7/Alt + Control |
| 8/Shift + Alt + Control |
| 9/Meta |
| 10/Meta + Shift |
| 11/Meta + Alt |
| 12/Meta + Alt + Shift |
| 13/Meta + Ctrl |
| 14/Meta + Ctrl + Shift |
| 15/Meta + Ctrl + Alt |
| 16/Meta + Ctrl + Alt + Shift |
ncurses defines no capabilities for modified F-keys;
terminal descriptions can refer to
names that
\%ncurses allocates at runtime to
"key codes" "." To use these keys in an \%ncurses program,
an application could do this:
.bP
using a list of extended key names,
ask tigetstr(3X) for their values, and
.bP
given the list of values,
ask key_defined(3X) for the key-code which
would be returned for those keys by wgetch(3X).
beginning with
\%ncurses 5.0 (1999)
In the source form of the terminal database, \%terminfo.src "," the section \*(``NCURSES USER-DEFINABLE CAPABILITIES\*(''. summarizes commonly-used user-defined capabilities employed in the terminal descriptions. Some of those features are mentioned in \%screen(1) or tmux(1).
"XTerm Control Sequences" provides further information on the \%xterm(1) features that are used in these extended capabilities.