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43 <H1 class="no-header">user_caps 5 2023-08-05 ncurses 6.4 File formats</H1>
45 <STRONG><A HREF="user_caps.5.html">user_caps(5)</A></STRONG> File formats <STRONG><A HREF="user_caps.5.html">user_caps(5)</A></STRONG>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 user_caps - user-defined terminfo capabilities
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>tic</STRONG> <STRONG>-x,</STRONG> <STRONG>infocmp</STRONG> <STRONG>-x</STRONG>
58 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
60 </PRE><H3><a name="h3-Background">Background</a></H3><PRE>
61 Before ncurses 5.0, terminfo databases used a <EM>fixed</EM> <EM>repertoire</EM> of
62 terminal capabilities designed for the SVr2 terminal database in 1984,
63 and extended in stages through SVr4 (1989), and standardized in the
64 Single Unix Specification beginning in 1995.
66 Most of the <EM>extensions</EM> in this fixed repertoire were additions to the
67 tables of boolean, numeric and string capabilities. Rather than change
68 the meaning of an existing capability, a new name was added. The
69 terminfo database uses a binary format; binary compatibility was
70 ensured by using a header which gave the number of items in the tables
71 for each type of capability. The standardization was incomplete:
73 <STRONG>o</STRONG> The <EM>binary</EM> <EM>format</EM> itself is not described in the X/Open Curses
74 documentation. Only the <EM>source</EM> <EM>format</EM> is described.
76 Library developers rely upon the SVr4 documentation, and reverse-
77 engineering the compiled terminfo files to match the binary format.
79 <STRONG>o</STRONG> Lacking a standard for the binary format, most implementations copy
80 the SVr2 binary format, which uses 16-bit signed integers, and is
81 limited to 4096-byte entries.
83 The format cannot represent very large numeric capabilities, nor
84 can it represent large numbers of special keyboard definitions.
86 <STRONG>o</STRONG> The tables of capability names differ between implementations.
88 Although they <EM>may</EM> provide all of the standard capability names, the
89 position in the tables differs because some features were added as
90 needed, while others were added (out of order) to comply with
93 While ncurses' repertoire of predefined capabilities is closest to
94 Solaris, Solaris's terminfo database has a few differences from the
95 list published by X/Open Curses. For example, ncurses can be
96 configured with tables which match the terminal databases for AIX,
97 HP-UX or OSF/1, rather than the default Solaris-like configuration.
99 <STRONG>o</STRONG> In SVr4 curses and ncurses, the terminal database is defined at
100 compile-time using a text file which lists the different terminal
103 In principle, the text-file can be extended, but doing this
104 requires recompiling and reinstalling the library. The text-file
105 used in ncurses for terminal capabilities includes details for
106 various systems past the documented X/Open Curses features. For
107 example, ncurses supports these capabilities in each configuration:
110 (meml) lock memory above cursor
116 (box1) box characters primary set
118 The memory lock/unlock capabilities were included because they were
119 used in the X11R6 terminal description for <STRONG>xterm(1)</STRONG>. The <EM>box1</EM>
120 capability is used in tic to help with terminal descriptions
123 During the 1990s, some users were reluctant to use terminfo in spite of
124 its performance advantages over termcap:
126 <STRONG>o</STRONG> The fixed repertoire prevented users from adding features for
127 unanticipated terminal improvements (or required them to reuse
128 existing capabilities as a workaround).
130 <STRONG>o</STRONG> The limitation to 16-bit signed integers was also mentioned.
131 Because termcap stores everything as a string, it could represent
134 Although termcap's extensibility was rarely used (it was never the
135 <EM>speaker</EM> who had actually used the feature), the criticism had a point.
136 ncurses 5.0 provided a way to detect nonstandard capabilities,
137 determine their type and optionally store and retrieve them in a way
138 which did not interfere with other applications. These are referred to
139 as <EM>user-defined</EM> <EM>capabilities</EM> because no modifications to the toolset's
140 predefined capability names are needed.
142 The ncurses utilities <STRONG>tic</STRONG> and <STRONG>infocmp</STRONG> have a command-line option "-x"
143 to control whether the nonstandard capabilities are stored or
144 retrieved. A library function <STRONG>use_extended_names</STRONG> is provided for the
147 When compiling a terminal database, if "-x" is set, <STRONG>tic</STRONG> will store a
148 user-defined capability if the capability name is not one of the
151 Because ncurses provides a termcap library interface, these user-
152 defined capabilities may be visible to termcap applications:
154 <STRONG>o</STRONG> The termcap interface (like all implementations of termcap)
155 requires that the capability names are 2-characters.
157 When the capability is simple enough for use in a termcap
158 application, it is provided as a 2-character name.
160 <STRONG>o</STRONG> There are other user-defined capabilities which refer to features
161 not usable in termcap, e.g., parameterized strings that use more
162 than two parameters or use more than the trivial expression support
163 provided by termcap. For these, the terminfo database should have
164 only capability names with 3 or more characters.
166 <STRONG>o</STRONG> Some terminals can send distinct strings for special keys (cursor-,
167 keypad- or function-keys) depending on modifier keys (shift,
168 control, etc.). While terminfo and termcap have a set of 60
169 predefined function-key names, to which a series of keys can be
170 assigned, that is insufficient for more than a dozen keys
171 multiplied by more than a couple of modifier combinations. The
172 ncurses database uses a convention based on <STRONG>xterm(1)</STRONG> to provide
173 extended special-key names.
175 Fitting that into termcap's limitation of 2-character names would
176 be pointless. These extended keys are available only with
180 </PRE><H3><a name="h3-Recognized-capabilities">Recognized capabilities</a></H3><PRE>
181 The ncurses library uses the user-definable capabilities. While the
182 terminfo database may have other extensions, ncurses makes explicit
185 AX <EM>boolean</EM>, asserts that the terminal interprets SGR 39 and SGR 49
186 by resetting the foreground and background color, respectively,
189 This is a feature recognized by the <STRONG>screen</STRONG> program as well.
191 E3 <EM>string</EM>, tells how to clear the terminal's scrollback buffer.
192 When present, the <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG> program sends this before clearing the
195 The command "<STRONG>tput</STRONG> <STRONG>clear</STRONG>" does the same thing.
197 NQ used to suppress a consistency check in tic for the ncurses
198 capabilities in user6 through user9 (u6, u7, u8 and u9) which
199 tell how to query the terminal's cursor position and its device
203 <EM>boolean</EM>, <EM>number</EM> <STRONG>or</STRONG> <EM>string</EM>, used to assert that the
204 <STRONG>set_a_foreground</STRONG> and <STRONG>set_a_background</STRONG> capabilities correspond to
205 <EM>direct</EM> <EM>colors</EM>, using an RGB (red/green/blue) convention. This
206 capability allows the <STRONG>color_content</STRONG> function to return
207 appropriate values without requiring the application to
208 initialize colors using <STRONG>init_color</STRONG>.
210 The capability type determines the values which ncurses sees:
213 implies that the number of bits for red, green and blue are
214 the same. Using the maximum number of colors, ncurses adds
215 two, divides that sum by three, and assigns the result to red,
216 green and blue in that order.
218 If the number of bits needed for the number of colors is not a
219 multiple of three, the blue (and green) components lose in
223 tells ncurses what result to add to red, green and blue. If
224 ncurses runs out of bits, blue (and green) lose just as in the
225 <EM>boolean</EM> case.
228 explicitly list the number of bits used for red, green and
229 blue components as a slash-separated list of decimal integers.
231 Because there are several RGB encodings in use, applications
232 which make assumptions about the number of bits per color are
233 unlikely to work reliably. As a trivial case, for example, one
234 could define <STRONG>RGB#1</STRONG> to represent the standard eight ANSI colors,
235 i.e., one bit per color.
237 U8 <EM>number</EM>, asserts that ncurses must use Unicode values for line-
238 drawing characters, and that it should ignore the alternate
239 character set capabilities when the locale uses UTF-8 encoding.
240 For more information, see the discussion of <STRONG>NCURSES_NO_UTF8_ACS</STRONG>
241 in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>.
243 Set this capability to a nonzero value to enable it.
245 XM <EM>string</EM>, override ncurses's built-in string which enables/disables
246 <STRONG>xterm(1)</STRONG> mouse mode.
248 ncurses sends a character sequence to the terminal to initialize
249 mouse mode, and when the user clicks the mouse buttons or (in
250 certain modes) moves the mouse, handles the characters sent back
251 by the terminal to tell it what was done with the mouse.
253 The mouse protocol is enabled when the <EM>mask</EM> passed in the
254 <STRONG>mousemask</STRONG> function is nonzero. By default, ncurses handles the
255 responses for the X11 xterm mouse protocol. It also knows about
256 the <EM>SGR</EM> <EM>1006</EM> xterm mouse protocol, but must to be told to look
257 for this specifically. It will not be able to guess which mode
258 is used, because the responses are enough alike that only
259 confusion would result.
261 The <STRONG>XM</STRONG> capability has a single parameter. If nonzero, the mouse
262 protocol should be enabled. If zero, the mouse protocol should
263 be disabled. ncurses inspects this capability if it is present,
264 to see whether the 1006 protocol is used. If so, it expects the
265 responses to use the <EM>SGR</EM> <EM>1006</EM> xterm mouse protocol.
267 The xterm mouse protocol is used by other terminal emulators.
268 The terminal database uses building-blocks for the various xterm
269 mouse protocols which can be used in customized terminal
272 The terminal database building blocks for this mouse feature also
273 have an experimental capability <EM>xm</EM>. The "xm" capability
274 describes the mouse response. Currently there is no interpreter
275 which would use this information to make the mouse support
276 completely data-driven.
278 <EM>xm</EM> shows the format of the mouse responses. In this experimental
279 capability, the parameters are
281 <EM>p1</EM> y-ordinate
283 <EM>p2</EM> x-ordinate
287 <EM>p4</EM> state, e.g., pressed or released
289 <EM>p5</EM> y-ordinate starting region
291 <EM>p6</EM> x-ordinate starting region
293 <EM>p7</EM> y-ordinate ending region
295 <EM>p8</EM> x-ordinate ending region
297 Here are examples from the terminal database for the most
298 commonly used xterm mouse protocols:
300 xterm+x11mouse|X11 xterm mouse protocol,
301 kmous=\E[M, XM=\E[?1000%?%p1%{1}%=%th%el%;,
303 %?%p4%t%p3%e%{3}%;%' '%+%c
307 xterm+sm+1006|xterm SGR-mouse,
308 kmous=\E[<, XM=\E[?1006;1000%?%p1%{1}%=%th%el%;,
315 </PRE><H3><a name="h3-Extended-key-definitions">Extended key-definitions</a></H3><PRE>
316 Several terminals provide the ability to send distinct strings for
317 combinations of modified special keys. There is no standard for what
320 Since 1999, <STRONG>xterm(1)</STRONG> has supported <EM>shift</EM>, <EM>control</EM>, <EM>alt</EM>, and <EM>meta</EM>
321 modifiers which produce distinct special-key strings. In a terminal
322 description, ncurses has no special knowledge of the modifiers used.
323 Applications can use the <EM>naming</EM> <EM>convention</EM> established for <STRONG>xterm</STRONG> to
324 find these special keys in the terminal description.
326 Starting with the curses convention that <EM>key</EM> <EM>names</EM> begin with "k" and
327 that shifted special keys are an uppercase name, ncurses' terminal
328 database defines these names to which a suffix is added:
330 <STRONG>Name</STRONG> <STRONG>Description</STRONG>
331 ---------------------------------------------------------------
332 kDC special form of kdch1 (delete character)
333 kDN special form of kcud1 (cursor down)
334 kEND special form of kend (End)
335 kHOM special form of khome (Home)
336 kLFT special form of kcub1 (cursor-left or cursor-back)
337 kNXT special form of knext (Next, or Page-Down)
338 kPRV special form of kprev (Prev, or Page-Up)
339 kRIT special form of kcuf1 (cursor-right, or cursor-forward)
340 kUP special form of kcuu1 (cursor-up)
342 These are the suffixes used to denote the modifiers:
344 <STRONG>Value</STRONG> <STRONG>Description</STRONG>
345 ----------------------------------
352 8 Shift + Alt + Control
356 12 Meta + Alt + Shift
358 14 Meta + Ctrl + Shift
360 16 Meta + Ctrl + Alt + Shift
362 None of these are predefined; terminal descriptions can refer to <EM>names</EM>
363 which ncurses will allocate at runtime to <EM>key-codes</EM>. To use these keys
364 in an ncurses program, an application could do this:
366 <STRONG>o</STRONG> using a list of extended key <EM>names</EM>, ask <STRONG><A HREF="curs_terminfo.3x.html">tigetstr(3x)</A></STRONG> for their
369 <STRONG>o</STRONG> given the list of values, ask <STRONG><A HREF="key_defined.3x.html">key_defined(3x)</A></STRONG> for the <EM>key-code</EM>
370 which would be returned for those keys by <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG>.
373 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
374 The "-x" extension feature of <STRONG>tic</STRONG> and <STRONG>infocmp</STRONG> has been adopted in
375 NetBSD curses. That implementation stores user-defined capabilities,
376 but makes no use of these capabilities itself.
379 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
380 <STRONG><A HREF="infocmp.1m.html">infocmp(1m)</A></STRONG>, <STRONG><A HREF="tic.1m.html">tic(1m)</A></STRONG>.
382 The terminal database section <EM>NCURSES</EM> <EM>USER-DEFINABLE</EM> <EM>CAPABILITIES</EM>
383 summarizes commonly-used user-defined capabilities which are used in
384 the terminal descriptions. Some of those features are mentioned in
385 <STRONG>screen(1)</STRONG> or <STRONG>tmux(1)</STRONG>.
387 <EM>XTerm</EM> <EM>Control</EM> <EM>Sequences</EM> provides further information on the <STRONG>xterm(1)</STRONG>
388 features which are used in these extended capabilities.
391 </PRE><H2><a name="h2-AUTHORS">AUTHORS</a></H2><PRE>
393 beginning with ncurses 5.0 (1999)
397 ncurses 6.4 2023-08-05 <STRONG><A HREF="user_caps.5.html">user_caps(5)</A></STRONG>
401 <li><a href="#h2-NAME">NAME</a></li>
402 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
403 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
405 <li><a href="#h3-Background">Background</a></li>
406 <li><a href="#h3-Recognized-capabilities">Recognized capabilities</a></li>
407 <li><a href="#h3-Extended-key-definitions">Extended key-definitions</a></li>
410 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
411 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
412 <li><a href="#h2-AUTHORS">AUTHORS</a></li>