xref: /openbsd/share/termtypes/termcap.5 (revision 9ea232b5)
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30.\"     from: @(#)termcap.5	6.11 (Berkeley) 3/6/93
31.\"
32.Dd $Mdocdate: January 23 2024 $
33.Dt TERMCAP 5
34.Os
35.Sh NAME
36.Nm termcap
37.Nd terminal capability database
38.Sh DESCRIPTION
39The
40.Nm
41file
42is a database describing terminals, used, for example, by
43.Xr vi 1
44and
45.Xr curses 3 .
46Terminals are described in
47.Nm
48by giving a set of capabilities that they have and by describing
49how operations are performed.
50Padding requirements and initialization sequences
51are included in
52.Nm .
53.Pp
54Entries in
55.Nm
56consist of a number of `:'-separated fields.
57The first entry for each terminal gives the names that are known for the
58terminal, separated by `|' characters.
59The first name given is the most common abbreviation for the terminal.
60The last name given should be a long name fully identifying the terminal,
61and all others are understood as synonyms for the terminal name.
62All names but the last should be in lower case and contain no blanks;
63the last name may well contain upper case characters and blanks for
64readability.
65.Pp
66Terminal names (except for the last, verbose entry)
67should be chosen using the following conventions.
68The particular piece of hardware making up the terminal
69should have a root name chosen, thus
70.Dq hp2621
71This name should not contain hyphens.
72Modes that the hardware can be in
73or user preferences
74should be indicated by appending a hyphen and an indicator of the mode.
75Therefore, a
76.Dq vt100
77in 132-column mode would be
78.Dq vt100-w .
79.Pp
80The following suffixes should be used where possible:
81.Bl -column "Suffix" "With automatic margins (usually default)" "Example"
82.It Sy Suffix Ta Sy Meaning Ta Sy Example
83.It \-w Ta "Wide mode (more than 80 columns)." Ta vt100-w
84.It \-am Ta "With automatic margins (usually default)." Ta vt100-am
85.It \-nam Ta "Without automatic margins." Ta vt100-nam
86.It Pf \- Ar n Ta "Number of lines on screen." Ta aaa-60
87.It \-na Ta "arrow keys (leave them in local)." Ta concept100-na
88.It Pf \- Ar np Ta "Number of pages of memory." Ta concept100-4p
89.It \-rv Ta "Reverse video." Ta concept100-rv
90.El
91.Sh CAPABILITIES
92The characters in the
93.Em Notes
94function
95field in the table have the following meanings
96(more than one may apply to a capability):
97.Bd -unfilled
98N	Indicates numeric parameter(s).
99P	Indicates that padding may be specified.
100*	Indicates that padding may be based on the number of lines affected.
101o	Indicates capability is obsolete.
102.Ed
103.Pp
104.Dq Obsolete
105capabilities have no
106.Xr terminfo 5
107equivalents, since they were considered useless,
108or are subsumed by other capabilities.
109New software should not rely on them at all.
110.Bl -column "i1-i3" "Type" "(NP*)" "Description"
111.It Sy Name Ta Sy Type Ta Sy Notes Ta Sy Description
112.It ae Ta str Ta (P) Ta "End alternate character set."
113.It AL Ta str Ta (NP*) Ta "Add"
114.Em n
115new blank lines
116.It al Ta str Ta (P*) Ta "Add new blank line."
117.It am Ta bool Ta "" Ta "Terminal has automatic margins."
118.It as Ta str Ta (P) Ta "Start alternate character set."
119.It bc Ta str Ta (o) Ta "Backspace if not"
120.Sy \&^H .
121.It bl Ta str Ta (P) Ta "Audible signal (bell)."
122.It bs Ta bool Ta (o) Ta "Terminal can backspace with"
123.Sy \&^H .
124.It bt Ta str Ta (P) Ta "Back tab."
125.It bw Ta bool Ta "" Ta Sy \&le
126(backspace) wraps from column 0 to last column.
127.It CC Ta str Ta "" Ta "Terminal settable command character in prototype."
128.It cd Ta str Ta (P*) Ta "Clear to end of display."
129.It ce Ta str Ta (P) Ta "Clear to end of line."
130.It ch Ta str Ta (NP) Ta "Set cursor column (horizontal position)."
131.It cl Ta str Ta (P*) Ta "Clear screen and home cursor."
132.It CM Ta str Ta (NP) Ta "Memory-relative cursor addressing."
133.It cm Ta str Ta (NP) Ta "Screen-relative cursor motion."
134.It co Ta num Ta "" Ta "Number of columns in a line (see"
135.Sx BUGS
136section below).
137.It cr Ta str Ta (P) Ta "Carriage return."
138.It cs Ta str Ta (NP) Ta "Change scrolling region (VT100)."
139.It ct Ta str Ta (P) Ta "Clear all tab stops."
140.It cv Ta str Ta (NP) Ta "Set cursor row (vertical position)."
141.It da Ta bool Ta "" Ta "Display may be retained above the screen."
142.It dB Ta num Ta (o) Ta "Milliseconds"
143.Sy \&bs
144delay needed (default 0).
145.It db Ta bool Ta "" Ta "Display may be retained below the screen."
146.It DC Ta str Ta (NP*) Ta "Delete"
147.Em n
148characters.
149.It dC Ta num Ta (o) Ta "Milliseconds"
150.Sy \&cr
151delay needed (default 0).
152.It dc Ta str Ta (P*) Ta "Delete character."
153.It dF Ta num Ta (o) Ta "Milliseconds"
154.Sy \&ff
155delay needed (default 0).
156.It DL Ta str Ta (NP*) Ta "Delete"
157.Ar n
158lines.
159.It dl Ta str Ta (P*) Ta "Delete line."
160.It dm Ta str Ta "" Ta "Enter delete mode."
161.It dN Ta num Ta (o) Ta "Milliseconds"
162.Sy \&nl
163delay needed (default 0).
164.It DO Ta str Ta (NP*) Ta "Move cursor down"
165.Ar n
166lines.
167.It do Ta str Ta "" Ta "Down one line."
168.It ds Ta str Ta "" Ta "Disable status line."
169.It dT Ta num Ta (o) Ta "Milliseconds of horizontal tab delay needed (default 0)."
170.It dV Ta num Ta (o) Ta "Milliseconds of vertical tab delay needed (default 0)."
171.It ec Ta str Ta (NP) Ta "Erase"
172.Ar n
173characters.
174.It ed Ta str Ta "" Ta "End delete mode."
175.It ei Ta str Ta "" Ta "End insert mode."
176.It eo Ta bool Ta "" Ta "Can erase overstrikes with a blank."
177.It EP Ta bool Ta (o) Ta "Even parity."
178.It es Ta bool Ta "" Ta "Escape can be used on the status line."
179.It ff Ta str Ta (P*) Ta "Hardcopy terminal page eject."
180.It fs Ta str Ta "" Ta "Return from status line."
181.It gn Ta bool Ta "" Ta "Generic line type, for example dialup, switch)."
182.It hc Ta bool Ta "" Ta "Hardcopy terminal."
183.It HD Ta bool Ta (o) Ta "Half-duplex."
184.It hd Ta str Ta "" Ta "Half-line down (forward 1/2 linefeed)."
185.It ho Ta str Ta (P) Ta "Home cursor."
186.It hs Ta bool Ta "" Ta "Has extra"
187.Dq status line .
188.It hu Ta str Ta "" Ta "Half-line up (reverse 1/2 linefeed)."
189.It hz Ta bool Ta "" Ta "Cannot print ``~'' (Hazeltine)."
190.It i1-i3 Ta str Ta "" Ta "Terminal initialization strings"
191.Pq Xr terminfo 5 No only
192.It IC Ta str Ta (NP*) Ta "Insert"
193.Ar n
194blank characters.
195.It ic Ta str Ta (P*) Ta "Insert character."
196.It if Ta str Ta "" Ta "Name of file containing initialization string."
197.It im Ta str Ta "" Ta "Enter insert mode."
198.It in Ta bool Ta "" Ta "Insert mode distinguishes nulls."
199.It iP Ta str Ta "" Ta "Pathname of program for initialization"
200.Pq Xr terminfo 5 No only
201.It ip Ta str Ta (P*) Ta "Insert pad after character inserted."
202.It is Ta str Ta "" Ta "Terminal initialization string"
203.Pf ( Nm termcap
204only).
205.It it Ta num Ta "" Ta "Tabs initially every"
206.Ar n
207positions.
208.It K1 Ta str Ta "" Ta "Sent by keypad upper left."
209.It K2 Ta str Ta "" Ta "Sent by keypad center."
210.It K3 Ta str Ta "" Ta "Sent by keypad upper right."
211.It K4 Ta str Ta "" Ta "Sent by keypad lower left."
212.It K5 Ta str Ta "" Ta "Sent by keypad lower right."
213.It k0-k9 Ta str Ta "" Ta "Sent by function keys 0-9."
214.It kA Ta str Ta "" Ta "Sent by insert-line key."
215.It ka Ta str Ta "" Ta "Sent by clear-all-tabs key."
216.It kb Ta str Ta "" Ta "Sent by backspace key."
217.It kC Ta str Ta "" Ta "Sent by clear-screen or erase key."
218.It kD Ta str Ta "" Ta "Sent by delete-character key."
219.It kd Ta str Ta "" Ta "Sent by down-arrow key."
220.It kE Ta str Ta "" Ta "Sent by clear-to-end-of-line key."
221.It ke Ta str Ta "" Ta "Out of"
222.Dq keypad transmit
223mode.
224.It kF Ta str Ta "" Ta "Sent by scroll-forward/down key."
225.It kH Ta str Ta "" Ta "Sent by home-down key."
226.It kh Ta str Ta "" Ta "Sent by home key."
227.It kI Ta str Ta "" Ta "Sent by insert-character or enter-insert-mode key."
228.It kL Ta str Ta "" Ta "Sent by delete-line key."
229.It kl Ta str Ta "" Ta "Sent by left-arrow key."
230.It kM Ta str Ta "" Ta "Sent by insert key while in insert mode."
231.It km Ta bool Ta "" Ta "Has a"
232.Dq meta
233key (shift, sets parity bit).
234.It kN Ta str Ta "" Ta "Sent by next-page key."
235.It kn Ta num Ta (o) Ta "Number of function"
236.Pq Sy \&k\&0 Ns \- Ns Sy \&k\&9
237keys (default 0).
238.It ko Ta str Ta (o) Ta "Termcap entries for other non-function keys."
239.It kP Ta str Ta "" Ta "Sent by previous-page key."
240.It kR Ta str Ta "" Ta "Sent by scroll-backward/up key."
241.It kr Ta str Ta "" Ta "Sent by right-arrow key."
242.It kS Ta str Ta "" Ta "Sent by clear-to-end-of-screen key."
243.It ks Ta str Ta "" Ta "Put terminal in"
244.Dq keypad transmit
245mode.
246.It kT Ta str Ta "" Ta "Sent by set-tab key."
247.It kt Ta str Ta "" Ta "Sent by clear-tab key."
248.It ku Ta str Ta "" Ta "Sent by up-arrow key."
249.It l0-l9 Ta str Ta "" Ta "Labels on function keys if not"
250.Dq \&f Ns Em n .
251.It LC Ta bool Ta (o) Ta "Lower-case only."
252.It LE Ta str Ta (NP) Ta "Move cursor left"
253.Ar n
254positions.
255.It le Ta str Ta (P) Ta "Move cursor left one position."
256.It li Ta num Ta "" Ta "Number of lines on screen or page (see"
257.Sx BUGS
258section below).
259.It ll Ta str Ta "" Ta "Last line, first column."
260.It lm Ta num Ta "" Ta "Lines of memory if >" Sy \&li
261(0 means varies).
262.It ma Ta str Ta (o) Ta "Arrow key map (used by"
263.Xr vi 1
264version 2 only).
265.It mb Ta str Ta "" Ta "Turn on blinking attribute."
266.It md Ta str Ta "" Ta "Turn on bold (extra bright) attribute."
267.It me Ta str Ta "" Ta "Turn off all attributes."
268.It mh Ta str Ta "" Ta "Turn on half-bright attribute."
269.It mi Ta bool Ta "" Ta "Safe to move while in insert mode."
270.It mk Ta str Ta "" Ta "Turn on blank attribute (characters invisible)."
271.It ml Ta str Ta (o) Ta "Memory lock on above cursor."
272.It mm Ta str Ta "" Ta "Turn on"
273.Dq meta mode
274(8th bit).
275.It mo Ta str Ta "" Ta "Turn off"
276.Dq meta mode .
277.It mp Ta str Ta "" Ta "Turn on protected attribute."
278.It mr Ta str Ta "" Ta "Turn on reverse-video attribute."
279.It ms Ta bool Ta "" Ta "Safe to move in standout modes."
280.It mu Ta str Ta (o) Ta "Memory unlock (turn off memory lock)."
281.It nc Ta bool Ta (o) Ta "No correctly-working"
282.Sy \&cr
283(Datamedia 2500, Hazeltine 2000).
284.It nd Ta str Ta "" Ta "Non-destructive space (cursor right)."
285.It NL Ta bool Ta (o)" Ta Sy \&\en No "is newline, not line feed."
286.It nl Ta str Ta (o) Ta "Newline character if not" Sy \en .
287.It ns Ta bool Ta (o) Ta "Terminal doesn't scroll."
288.It nw Ta str Ta (P) Ta "Newline (behaves like"
289.Sy \&cr
290followed by
291.Sy \&do ) .
292.It OP Ta bool Ta (o) Ta "Odd parity."
293.It os Ta bool Ta "" Ta "Terminal overstrikes."
294.It pb Ta num Ta "" Ta "Lowest baud where delays are required."
295.It pc Ta str Ta "" Ta "Pad character (default NUL)."
296.It pf Ta str Ta "" Ta "Turn off the printer."
297.It pk Ta str Ta "" Ta "Program function key"
298.Em n
299to type string
300.Em s
301.Pq Xr terminfo 5 No only
302.It pl Ta str Ta "" Ta "Program function key"
303.Em n
304to execute string
305.Em s
306.Pq Xr terminfo 5 No only
307.It pO Ta str Ta (N) Ta "Turn on the printer for"
308.Em n
309bytes.
310.It po Ta str Ta "" Ta "Turn on the printer."
311.It ps Ta str Ta "" Ta "Print contents of the screen."
312.It pt Ta bool Ta (o) Ta "Has hardware tabs (may need to be set with"
313.Sy \&is ) .
314.It px Ta str Ta "" Ta "Program function key"
315.Em n
316to transmit string
317.Em s
318.Pq Xr terminfo 5 No only
319.It r1-r3 Ta str Ta "" Ta "Reset terminal completely to sane modes"
320.Pq Xr terminfo 5 No only
321.It rc Ta str Ta (P) Ta "Restore cursor to position of last"
322.Sy \&sc .
323.It rf Ta str Ta "" Ta "Name of file containing reset codes."
324.It RI Ta str Ta (NP) Ta "Move cursor right"
325.Em n
326positions.
327.It rp Ta str Ta (NP*) Ta "Repeat character"
328.Em c n
329times.
330.It rs Ta str Ta "" Ta "Reset terminal completely to sane modes"
331.Pf ( Nm termcap
332only).
333.It sa Ta str Ta (NP) Ta "Define the video attributes."
334.It sc Ta str Ta (P) Ta "Save cursor position."
335.It se Ta str Ta "" Ta "End standout mode."
336.It SF Ta str Ta (NP*) Ta "Scroll forward"
337.Em n
338lines.
339.It sf Ta str Ta (P) Ta "Scroll text up."
340.It sg Ta num Ta "" Ta "Number of garbage chars left by"
341.Sy \&so
342or
343.Sy \&se
344(default 0).
345.It so Ta str Ta "" Ta "Begin standout mode."
346.It SR Ta str Ta (NP*) Ta "Scroll backward"
347.Em n
348lines.
349.It sr Ta str Ta (P) Ta "Scroll text down."
350.It st Ta str Ta "" Ta "Set a tab in all rows, current column."
351.It ta Ta str Ta (P) Ta "Tab to next 8-position hardware tab stop."
352.It tc Ta str Ta "" Ta "Entry of similar terminal; must be last."
353.It te Ta str Ta "" Ta "String to end programs that use"
354.Nm .
355.It ti Ta str Ta "" Ta "String to begin programs that use"
356.Nm .
357.It ts Ta str Ta (N) Ta "Go to status line, column"
358.Em n .
359.It UC Ta bool Ta (o) Ta "Upper-case only."
360.It uc Ta str Ta "" Ta "Underscore one character and move past it."
361.It ue Ta str Ta "" Ta "End underscore mode."
362.It ug Ta num Ta "" Ta "Number of garbage chars left by"
363.Sy \&us
364or
365.Sy \&ue
366(default 0).
367.It ul Ta bool Ta "" Ta "Underline character overstrikes."
368.It UP Ta str Ta (NP*) Ta "Move cursor up"
369.Em n
370lines.
371.It up Ta str Ta "" Ta "Upline (cursor up)."
372.It us Ta str Ta "" Ta "Start underscore mode."
373.It vb Ta str Ta "" Ta "Visible bell (must not move cursor)."
374.It ve Ta str Ta "" Ta "Make cursor appear normal (undo"
375.Sy \&vs Ns / Ns Sy \&vi ) .
376.It vi Ta str Ta "" Ta "Make cursor invisible."
377.It vs Ta str Ta "" Ta "Make cursor very visible."
378.It vt Ta num Ta "" Ta "Virtual terminal number (not supported on all systems)."
379.It wi Ta str Ta (N) Ta "Set current window."
380.It ws Ta num Ta "" Ta "Number of columns in status line."
381.It xb Ta bool Ta "" Ta "Beehive"
382.Pf ( "f1=" Dv ESC ,
383.Pf "f2=" Sy \&^C ) .
384.It xn Ta bool Ta "" Ta "Newline ignored after 80 columns (Concept)."
385.It xo Ta bool Ta "" Ta "Terminal uses xoff/xon"
386.Pq Dv DC3 Ns / Ns Dv DC1
387handshaking.
388.It xr Ta bool Ta (o) Ta "Return acts like"
389.Sy "ce cr nl"
390(Delta Data).
391.It xs Ta bool Ta "" Ta "Standout not erased by overwriting (Hewlett-Packard)."
392.It xt Ta bool Ta "" Ta "Tabs ruin, magic"
393.Sy \&so
394char (Teleray 1061).
395.It xx Ta bool Ta (o) Ta "Tektronix 4025 insert-line."
396.El
397.Ss A Sample Entry
398The following entry, which describes the Concept\-100, is among the more
399complex entries in the
400.Nm
401file as of this writing.
402.Bd -literal
403ca\||\|concept100\||\|c100\||\|concept\||\|c104\||\|concept100-4p\||\|HDS Concept\-100:\e
404	:al=3*\eE^R:am:bl=^G:cd=16*\eE^C:ce=16\eE^U:cl=2*^L:cm=\eEa%+ %+ :\e
405	:co#80:.cr=9^M:db:dc=16\eE^A:dl=3*\eE^B:do=^J:ei=\eE\e200:eo:im=\eE^P:in:\e
406	:ip=16*:is=\eEU\eEf\eE7\eE5\eE8\eEl\eENH\eEK\eE\e200\eEo&\e200\eEo\e47\eE:k1=\eE5:\e
407	:k2=\eE6:k3=\eE7:kb=^h:kd=\eE<:ke=\eEx:kh=\eE?:kl=\eE>:kr=\eE=:ks=\eEX:\e
408	:ku=\eE;:le=^H:li#24:mb=\eEC:me=\eEN\e200:mh=\eEE:mi:mk=\eEH:mp=\eEI:\e
409	:mr=\eED:nd=\eE=:pb#9600:rp=0.2*\eEr%.%+ :se=\eEd\eEe:sf=^J:so=\eEE\eED:\e
410	:.ta=8\et:te=\eEv    \e200\e200\e200\e200\e200\e200\eEp\er\en:\e
411	:ti=\eEU\eEv  8p\eEp\er:ue=\eEg:ul:up=\eE;:us=\eEG:\e
412	:vb=\eEk\e200\e200\e200\e200\e200\e200\e200\e200\e200\e200\e200\e200\e200\e200\eEK:\e
413	:ve=\eEw:vs=\eEW:vt#8:xn:\e
414	:bs:cr=^M:dC#9:dT#8:nl=^J:ta=^I:pt:
415.Ed
416.Pp
417Entries may continue onto multiple lines by giving a
418.Ql \e
419as the last character of a line, and empty fields
420may be included for readability (here between the last field on a line
421and the first field on the next).
422Comments may be included on lines beginning with
423.Ql # .
424.Ss Types of Capabilities
425Capabilities in
426.Nm
427are of three types: Boolean capabilities,
428which indicate particular features that the terminal has;
429numeric capabilities,
430giving the size of the display or the size of other attributes;
431and string capabilities,
432which give character sequences that can be used to perform particular
433terminal operations.
434All capabilities have two-letter codes.
435For instance, the fact that
436the Concept has
437.Em automatic margins
438(an automatic return and linefeed
439when the end of a line is reached) is indicated by the Boolean capability
440.Sy \&am .
441Hence the description of the Concept includes
442.Sy \&am .
443.Pp
444Boolean capabilities are defined by their name,
445.Sy \&fo .
446They have no argument.
447The presence of a boolean capability name sets its value to
448.Sy \&true .
449A capability value will be reverted to
450.Sy \&false ,
451by appending a
452.Sy \&@
453char after the name, such as
454.Sy \&fo@ .
455.Pp
456Numeric capabilities are followed by the character `#' then the value.
457In the example above
458.Sy \&co ,
459which indicates the number of columns the display has,
460gives the value `80' for the Concept.
461.Pp
462Finally, string-valued capabilities, such as
463.Sy \&ce
464(clear-to-end-of-line
465sequence) are given by the two-letter code, an `=', then a string
466ending at the next following `:'.
467A delay in milliseconds may appear after
468the `=' in such a capability,
469which causes padding characters to be supplied by
470.Xr tputs 3
471after the remainder of the string is sent to provide this delay.
472The delay can be either a number,
473such as `20', or a number followed by
474an `*',
475such as `3*'.
476An `*' indicates that the padding required is proportional
477to the number of lines affected by the operation, and the amount given is
478the per-affected-line padding required.
479(In the case of insert-character,
480the factor is still the number of
481.Em lines
482affected;
483this is always 1 unless the terminal has
484.Sy \&in
485and the software uses it.)
486When an `*' is specified, it is sometimes useful to give a delay of the form
487`3.5' to specify a delay per line to tenths of milliseconds.
488(Only one decimal place is allowed.)
489.Pp
490A number of escape sequences are provided in the string-valued capabilities
491for easy encoding of control characters there.
492.Sy \&\eE
493maps to an
494.Dv ESC
495character,
496.Sy \&^X
497maps to a control-X for any appropriate X,
498and the sequences
499.Sy \&\en
500.Sy \&\er
501.Sy \&\et
502.Sy \&\eb
503.Sy \&\ef
504map to linefeed, return, tab, backspace, and formfeed, respectively.
505Finally, characters may be given as three octal digits after a
506.Sy \&\e ,
507and the characters
508.Sy \&^
509and
510.Sy \&\e
511may be given as
512.Sy \&\e^
513and
514.Sy \&\e\e .
515If it is necessary to place a
516.Sy \&:
517in a capability, it must be escaped in octal as
518.Sy \&\e072 .
519If it is necessary to place a
520.Dv NUL
521character in a string capability, it must be encoded as
522.Sy \&\e200 .
523(The routines that deal with
524.Nm
525use C strings and strip the high bits of the output very late, so that a
526.Sy \&\e200
527comes out as a
528.Sy \&\e000
529would.)
530.Pp
531Sometimes individual capabilities must be commented out.
532To do this, put a period before the capability name.
533For example, see the first
534.Sy \&cr
535and
536.Sy \&ta
537in the example above.
538.Ss Preparing Descriptions
539The most effective way to prepare a terminal description is by imitating
540the description of a similar terminal in
541.Nm
542and to build up a description gradually, using partial descriptions
543with
544.Xr vi 1
545to check that they are correct.
546Be aware that a very unusual terminal may expose deficiencies in
547the ability of the
548.Nm
549file to describe it
550or bugs in
551.Xr vi 1 .
552To easily test a new terminal description you are working on
553you can put it in your home directory in a file called
554.Pa .termcap
555and programs will look there before looking in
556.Pa /usr/share/misc/termcap .
557You can also set the environment variable
558.Ev TERMPATH
559to a list of absolute file pathnames (separated by spaces or colons),
560one of which contains the description you are working on,
561and programs will search them in the order listed, and nowhere else.
562See
563.Xr termcap 3 .
564The
565.Ev TERMCAP
566environment variable is usually set to the
567.Nm
568entry itself
569to avoid reading files when starting up a program.
570.Pp
571To get the padding for insert-line right
572(if the terminal manufacturer did not document it),
573a severe test is to use
574.Xr vi 1
575to edit
576.Pa /etc/passwd
577at 9600 baud, delete roughly 16 lines from the middle of the screen,
578then hit the `u' key several times quickly.
579If the display messes up, more padding is usually needed.
580A similar test can be used for insert-character.
581.Ss Basic Capabilities
582The number of columns on each line of the display is given by the
583.Sy \&co
584numeric capability.
585If the display is a terminal,
586then the
587number of lines on the screen is given by the
588.Sy \&li
589capability.
590If the display wraps around to the beginning of the next line when
591the cursor reaches the right margin, then it should have the
592.Sy \&am
593capability.
594If the terminal can clear its screen,
595the code to do this is given by the
596.Sy \&cl
597string capability.
598If the terminal overstrikes
599(rather than clearing the position when a character is overwritten),
600it should have the
601.Sy \&os
602capability.
603If the terminal is a printing terminal,
604with no soft copy unit,
605give it both
606.Sy \&hc
607and
608.Sy \&os .
609.Pf ( Sy \&os
610applies to storage scope terminals,
611such as the Tektronix 4010 series,
612as well as to hard copy and
613.Tn APL
614terminals.)
615If there is a code to move the cursor to the left edge of the current row,
616give this as
617.Sy \&cr .
618(Normally this will be carriage-return,
619.Sy \&^M . )
620If there is a code to produce an audible signal (bell, beep, etc.),
621give this as
622.Sy \&bl .
623.Pp
624If there is a code (such as backspace)
625to move the cursor one position to the left,
626that capability should be given as
627.Sy \&le .
628Similarly,
629codes to move to the right, up, and down
630should be given as
631.Sy \&nd ,
632.Sy \&up ,
633and
634.Sy \&do ,
635respectively.
636These
637.Em local cursor motions
638should not alter the text they pass over;
639for example, you would not normally use
640.Dq nd=\ \&
641unless the terminal has the
642.Sy \&os
643capability,
644because the space would erase the character moved over.
645.Pp
646A very important point here is that the local cursor motions encoded
647in
648.Nm
649have undefined behavior at the left and top edges of a terminal.
650Programs should never attempt to backspace around the left edge,
651unless
652.Sy \&bw
653is given, and never attempt to go up off the top
654using local cursor motions.
655.Pp
656In order to scroll text up,
657a program goes to the bottom left corner of the screen and sends the
658.Sy \&sf
659(index) string.
660To scroll text down,
661a program goes to the top left corner of the screen and sends the
662.Sy \&sr
663(reverse index) string.
664The strings
665.Sy \&sf
666and
667.Sy \&sr
668have undefined behavior
669when not on their respective corners of the screen.
670Parameterized versions of the scrolling sequences are
671.Sy \&SF
672and
673.Sy \&SR ,
674which have the same semantics as
675.Sy \&sf
676and
677.Sy \&sr
678except that they take one parameter
679and scroll that many lines.
680They also have undefined behavior
681except at the appropriate corner of the screen.
682.Pp
683The
684.Sy \&am
685capability tells whether the cursor sticks at the right
686edge of the screen when text is output there,
687but this does not necessarily apply to
688.Sy \&nd
689from the last column.
690Leftward local motion is defined from the left edge only when
691.Sy \&bw
692is given; then an
693.Sy \&le
694from the left edge will move to the right edge of the previous row.
695This is useful for drawing a box around the edge of the screen,
696for example.
697If the terminal has switch-selectable automatic margins,
698the
699.Nm
700description usually assumes that this feature is on, i.e.\&
701.Sy \&am .
702If the terminal has a command
703that moves to the first column of the next line,
704that command can be given as
705.Sy \&nw
706(newline).
707It is permissible for this to clear the remainder of the current line,
708so if the terminal has no correctly working
709.Tn \&CR
710and
711.Tn \&LF
712it may still be possible to craft a working
713.Sy \&nw
714out of one or both of them.
715.Pp
716These capabilities suffice to describe hardcopy and
717.Dq glass-tty
718terminals.
719Thus the Teletype model 33 is described as
720.Bd -literal -offset indent
721T3\||\|tty33\||\|33\||\|tty\||\|Teletype model 33:\e
722	:bl=^G:co#72:cr=^M:do=^J:hc:os:
723.Ed
724.Pp
725and the Lear Siegler
726.Tn ADM Ns \-3
727is described as
728.Bd -literal -offset indent
729l3\||\|adm3\||\|3\||\|LSI ADM-3:\e
730:am:bl=^G:cl=^Z:co#80:cr=^M:do=^J:le=^H:li#24:sf=^J:
731.Ed
732.Ss Parameterized Strings
733Cursor addressing and other strings requiring parameters
734are described by a
735parameterized string capability, with
736.Xr printf 3 Ns \-like
737escapes
738.Sy \&%x
739in it,
740while other characters are passed through unchanged.
741For example, to address the cursor the
742.Sy \&cm
743capability is given, using two parameters: the row and column to move to.
744(Rows and columns are numbered from zero and refer to the physical screen
745visible to the user, not to any unseen memory.
746If the terminal has memory-relative cursor addressing,
747that can be indicated by an analogous
748.Sy \&CM
749capability.)
750.Pp
751The
752.Sy \&%
753encodings have the following meanings:
754.Pp
755.Bl -tag -width "%>xy" -compact
756.It %%
757output `%'
758.It %d
759output value as in
760.Xr printf 3
761%d
762.It %2
763output value as in
764.Xr printf 3
765%2d
766.It %3
767output value as in
768.Xr printf 3
769%3d
770.It %.
771output value as in
772.Xr printf 3
773%c
774.It %+ Ns Em x
775add
776.Em x
777to value, then do %.
778.It %> Ns Em \&xy
779if
780value >
781.Em x
782then add
783.Em y ,
784no output
785.It %r
786reverse order of two parameters, no output
787.It %i
788increment by one, no output
789.It %n
790exclusive-or all parameters with 0140 (Datamedia 2500)
791.It \&%B
792BCD (16*(value/10)) + (value%10), no output
793.It \&%D
794Reverse coding (value \- 2*(value%16)), no output (Delta Data)
795.El
796.Pp
797Consider the Hewlett-Packard 2645, which, to get to row 3 and column 12, needs
798to be sent
799.Dq \eE&a12c03Y
800padded for 6 milliseconds.
801Note that the order
802of the row and column coordinates is reversed here
803and that the row and column
804are sent as two-digit integers.
805Thus its
806.Sy \&cm
807capability is
808.Dq Li cm=6\eE&a%r%2c%2Y .
809.Pp
810The Datamedia 2500 needs the current row and column sent
811encoded in binary using
812.Dq \&%. .
813Terminals that use
814.Dq \&%.
815need to be able to
816backspace the cursor
817.Pq Sy \&le
818and to move the cursor up one line on the screen
819.Pq Sy \&up .
820This is necessary because it is not always safe to transmit
821.Sy \&\en ,
822.Sy \&^D ,
823and
824.Sy \&\er ,
825as the system may change or discard them.
826(Programs using
827.Nm
828must set terminal modes so that tabs are not expanded, so
829.Sy \&\et
830is safe to send.
831This turns out to be essential for the Ann Arbor 4080.)
832.Pp
833A final example is the Lear Siegler
834.Tn ADM Ns \-3a ,
835which offsets row and column
836by a blank character, thus
837.Dq Li cm=\eE=%+ %+\ \& .
838.Pp
839Row or column absolute cursor addressing
840can be given as single parameter capabilities
841.Sy \&ch
842(horizontal position absolute) and
843.Sy \&cv
844(vertical position absolute).
845Sometimes these are shorter than the more general two-parameter sequence
846(as with the Hewlett-Packard 2645) and can be used in preference to
847.Sy \&cm .
848If there are parameterized local motions
849(e.g., move
850.Ar n
851positions to the right)
852these can be given as
853.Sy \&DO ,
854.Sy \&LE ,
855.Sy \&RI ,
856and
857.Sy \&UP
858with a single parameter indicating how many positions to move.
859These are primarily useful if the terminal does not have
860.Sy \&cm ,
861such as the Tektronix 4025.
862.Ss Cursor Motions
863If the terminal has a fast way to home the cursor
864(to the very upper left corner of the screen), this can be given as
865.Sy \&ho .
866Similarly, a fast way of getting to the lower left-hand corner
867can be given as
868.Sy \&ll ;
869this may involve going up with
870.Sy \&up
871from the home position,
872but a program should never do this itself (unless
873.Sy \&ll
874does), because it can
875make no assumption about the effect of moving up from the home position.
876Note that the home position is the same as
877cursor address (0,0): to the top left corner of the screen, not of memory.
878(Therefore, the
879.Dq \eEH
880sequence on Hewlett-Packard terminals
881cannot be used for
882.Sy \&ho . )
883.Ss Area Clears
884If the terminal can clear from the current position to the end of the
885line, leaving the cursor where it is, this should be given as
886.Sy \&ce .
887If the terminal can clear from the current position to the end of the
888display, this should be given as
889.Sy \&cd .
890.Sy \&cd
891must only be invoked from the first column of a line.
892(Therefore,
893it can be simulated by a request to delete a large number of lines,
894if a true
895.Sy \&cd
896is not available.)
897.Ss Insert/Delete Line
898If the terminal can open a new blank line
899before the line containing the cursor,
900this should be given as
901.Sy \&al ;
902this must be invoked only from the first
903position of a line.
904The cursor must then appear at the left of the newly blank line.
905If the terminal can delete the line that the cursor is on, this
906should be given as
907.Sy \&dl ;
908this must only be used from the first position on
909the line to be deleted.
910Versions of
911.Sy \&al
912and
913.Sy \&dl
914which take a single parameter
915and insert or delete that many lines
916can be given as
917.Sy \&AL
918and
919.Sy \&DL .
920If the terminal has a settable scrolling region
921(like the VT100),
922the command to set this can be described with the
923.Sy \&cs
924capability,
925which takes two parameters: the top and bottom lines of the scrolling region.
926The cursor position is, alas, undefined after using this command.
927It is possible to get the effect of insert or delete line
928using this command \(em the
929.Sy \&sc
930and
931.Sy \&rc
932(save and restore cursor) commands are also useful.
933Inserting lines at the top or bottom of the screen can also be done using
934.Sy \&sr
935or
936.Sy \&sf
937on many terminals without a true insert/delete line,
938and is often faster even on terminals with those features.
939.Pp
940If the terminal has the ability to define a window as part of memory
941which all commands affect, it should be given as the parameterized string
942.Sy \&wi .
943The four parameters are the starting and ending lines in memory
944and the starting and ending columns in memory, in that order.
945(This
946.Xr terminfo 5
947capability is described for completeness.
948It is unlikely that any
949.Nm Ns -using
950program will support it.)
951.Pp
952If the terminal can retain display memory above the screen, then the
953.Sy \&da
954capability should be given;
955if display memory can be retained
956below, then
957.Sy \&db
958should be given.
959These indicate
960that deleting a line or scrolling may bring non-blank lines up from below
961or that scrolling back with
962.Sy \&sr
963may bring down non-blank lines.
964.Ss Insert/Delete Character
965There are two basic kinds of intelligent terminals with respect to
966insert/delete character that can be described using
967.Nm .
968The most common insert/delete character operations affect only the characters
969on the current line and shift characters off the end of the line rigidly.
970Other terminals, such as the Concept\-100 and the Perkin Elmer Owl, make
971a distinction between typed and untyped blanks on the screen, shifting
972upon an insert or delete only to an untyped blank on the screen which is
973either eliminated or expanded to two untyped blanks.
974You can determine
975the kind of terminal you have by clearing the screen then typing
976text separated by cursor motions.
977Type
978.Dq Li abc\ \ \ \ def
979using local
980cursor motions (not spaces) between the
981.Dq abc
982and the
983.Dq def .
984Then position the cursor before the
985.Dq abc
986and put the terminal in insert
987mode.
988If typing characters causes the rest of the line to shift
989rigidly and characters to fall off the end, then your terminal does
990not distinguish between blanks and untyped positions.
991If the
992.Dq abc
993shifts over to the
994.Dq def
995which then move together around the end of the
996current line and onto the next as you insert, then you have the second type of
997terminal and should give the capability
998.Sy \&in ,
999which stands for
1000.Dq insert null .
1001While these are two logically separate attributes
1002(one line
1003.Em \&vs .
1004multi-line insert mode,
1005and special treatment of untyped spaces),
1006we have seen no terminals whose insert
1007mode cannot be described with the single attribute.
1008.Pp
1009.Nm
1010can describe both terminals that have an insert mode and terminals
1011that send a simple sequence to open a blank position on the current line.
1012Give as
1013.Sy \&im
1014the sequence to get into insert mode.
1015Give as
1016.Sy \&ei
1017the sequence to leave insert mode.
1018Now give as
1019.Sy \&ic
1020any sequence that needs to be sent just before
1021each character to be inserted.
1022Most terminals with a true insert mode
1023will not give
1024.Sy \&ic ;
1025terminals that use a sequence to open a screen
1026position should give it here.
1027(If your terminal has both,
1028insert mode is usually preferable to
1029.Sy \&ic .
1030Do not give both unless the terminal actually requires both to be used
1031in combination.)
1032If post-insert padding is needed, give this as a number of milliseconds
1033in
1034.Sy \&ip
1035(a string option).
1036Any other sequence that may need to be
1037sent after insertion of a single character can also be given in
1038.Sy \&ip .
1039If your terminal needs to be placed into an `insert mode'
1040and needs a special code preceding each inserted character,
1041then both
1042.Sy \&im Ns / Sy \&ei
1043and
1044.Sy \&ic
1045can be given, and both will be used.
1046The
1047.Sy \&IC
1048capability, with one parameter
1049.Em n ,
1050will repeat the effects of
1051.Sy \&ic
1052.Em n
1053times.
1054.Pp
1055It is occasionally necessary to move around while in insert mode
1056to delete characters on the same line
1057(e.g., if there is a tab after the insertion position).
1058If your terminal allows motion while in
1059insert mode, you can give the capability
1060.Sy \&mi
1061to speed up inserting
1062in this case.
1063Omitting
1064.Sy \&mi
1065will affect only speed.
1066Some terminals
1067(notably Datamedia's) must not have
1068.Sy \&mi
1069because of the way their
1070insert mode works.
1071.Pp
1072Finally, you can specify
1073.Sy \&dc
1074to delete a single character,
1075.Sy \&DC
1076with one parameter
1077.Em n
1078to delete
1079.Em n
1080characters,
1081and delete mode by giving
1082.Sy \&dm
1083and
1084.Sy \&ed
1085to enter and exit delete mode
1086(which is any mode the terminal needs to be placed in for
1087.Sy \&dc
1088to work).
1089.Ss Highlighting, Underlining, and Visible Bells
1090If your terminal has one or more kinds of display attributes,
1091these can be represented in a number of different ways.
1092You should choose one display form as
1093.Em standout mode ,
1094representing a good high-contrast, easy-on-the-eyes format
1095for highlighting error messages and other attention getters.
1096(If you have a choice, reverse video plus half-bright is good,
1097or reverse video alone.)
1098The sequences to enter and exit standout mode
1099are given as
1100.Sy \&so
1101and
1102.Sy \&se ,
1103respectively.
1104If the code to change into or out of standout
1105mode leaves one or even two blank spaces or garbage characters on the screen,
1106as the
1107.Tn TVI
1108912 and Teleray 1061 do,
1109then
1110.Sy \&sg
1111should be given to tell how many characters are left.
1112.Pp
1113Codes to begin underlining and end underlining can be given as
1114.Sy \&us
1115and
1116.Sy \&ue ,
1117respectively.
1118Underline mode change garbage is specified by
1119.Sy \&ug ,
1120similar to
1121.Sy \&sg .
1122If the terminal has a code to underline the current character and move
1123the cursor one position to the right,
1124such as the Microterm Mime,
1125this can be given as
1126.Sy \&uc .
1127.Pp
1128Other capabilities to enter various highlighting modes include
1129.Sy \&mb
1130(blinking),
1131.Sy \&md
1132(bold or extra bright),
1133.Sy \&mh
1134(dim or half-bright),
1135.Sy \&mk
1136(blanking or invisible text),
1137.Sy \&mp
1138(protected),
1139.Sy \&mr
1140(reverse video),
1141.Sy \&me
1142(turn off
1143.Em all
1144attribute modes),
1145.Sy \&as
1146(enter alternate character set mode), and
1147.Sy \&ae
1148(exit alternate character set mode).
1149Turning on any of these modes singly may or may not turn off other modes.
1150.Pp
1151If there is a sequence to set arbitrary combinations of mode,
1152this should be given as
1153.Sy \&sa
1154(set attributes), taking 9 parameters.
1155Each parameter is either 0 or 1,
1156as the corresponding attributes is on or off.
1157The 9 parameters are, in order: standout, underline, reverse, blink,
1158dim, bold, blank, protect, and alternate character set.
1159Not all modes need be supported by
1160.Sy \&sa ,
1161only those for which corresponding attribute commands exist.
1162(It is unlikely that a
1163.Nm Ns -using
1164program will support this capability, which is defined for compatibility
1165with
1166.Xr terminfo 5 . )
1167.Pp
1168Terminals with the
1169.Dq magic cookie
1170glitches
1171.Pf ( Sy \&sg
1172and
1173.Sy \&ug ) ,
1174rather than maintaining extra attribute bits for each character cell,
1175instead deposit special
1176.Dq cookies ,
1177or
1178.Dq garbage characters ,
1179when they receive mode-setting sequences,
1180which affect the display algorithm.
1181.Pp
1182Some terminals,
1183such as the Hewlett-Packard 2621,
1184automatically leave standout
1185mode when they move to a new line or when the cursor is addressed.
1186Programs using standout mode
1187should exit standout mode on such terminals
1188before moving the cursor or sending a newline.
1189On terminals where this is not a problem,
1190the
1191.Sy \&ms
1192capability should be present
1193to say that this overhead is unnecessary.
1194.Pp
1195If the terminal has
1196a way of flashing the screen to indicate an error quietly
1197(a bell replacement),
1198this can be given as
1199.Sy \&vb ;
1200it must not move the cursor.
1201.Pp
1202If the cursor needs to be made more visible than normal
1203when it is not on the bottom line
1204(to change, for example, a non-blinking underline into an easier-to-find
1205block or blinking underline),
1206give this sequence as
1207.Sy \&vs .
1208If there is a way to make the cursor completely invisible, give that as
1209.Sy \&vi .
1210The capability
1211.Sy \&ve ,
1212which undoes the effects of both of these modes,
1213should also be given.
1214.Pp
1215If your terminal correctly displays underlined characters
1216(with no special codes needed)
1217even though it does not overstrike,
1218then you should give the capability
1219.Sy \&ul .
1220If overstrikes are erasable with a blank,
1221this should be indicated by giving
1222.Sy \&eo .
1223.Ss Keypad
1224If the terminal has a keypad that transmits codes when the keys are pressed,
1225this information can be given.
1226Note that it is not possible to handle
1227terminals where the keypad only works in local mode
1228(this applies, for example, to the unshifted Hewlett-Packard 2621 keys).
1229If the keypad can be set to transmit or not transmit,
1230give these codes as
1231.Sy \&ks
1232and
1233.Sy \&ke .
1234Otherwise the keypad is assumed to always transmit.
1235The codes sent by the left-arrow, right-arrow, up-arrow, down-arrow,
1236and home keys can be given as
1237.Sy \&kl ,
1238.Sy \&kr ,
1239.Sy \&ku ,
1240.Sy \&kd ,
1241and
1242.Sy \&kh ,
1243respectively.
1244If there are function keys such as f0, f1, ..., f9, the codes they send
1245can be given as
1246.Sy \&k0 ,
1247.Sy \&k1 ,
1248\&...,
1249.Sy \&k9 .
1250If these keys have labels other than the default f0 through f9, the labels
1251can be given as
1252.Sy \&l0 ,
1253.Sy \&l1 ,
1254\&...,
1255.Sy \&l9 .
1256The codes transmitted by certain other special keys can be given:
1257.Sy \&kH
1258(home down),
1259.Sy \&kb
1260(backspace),
1261.Sy \&ka
1262(clear all tabs),
1263.Sy \&kt
1264(clear the tab stop in this column),
1265.Sy \&kC
1266(clear screen or erase),
1267.Sy \&kD
1268(delete character),
1269.Sy \&kL
1270(delete line),
1271.Sy \&kM
1272(exit insert mode),
1273.Sy \&kE
1274(clear to end of line),
1275.Sy \&kS
1276(clear to end of screen),
1277.Sy \&kI
1278(insert character or enter insert mode),
1279.Sy \&kA
1280(insert line),
1281.Sy \&kN
1282(next page),
1283.Sy \&kP
1284(previous page),
1285.Sy \&kF
1286(scroll forward/down),
1287.Sy \&kR
1288(scroll backward/up), and
1289.Sy \&kT
1290(set a tab stop in this column).
1291In addition, if the keypad has a 3 by 3 array of keys
1292including the four arrow keys, then the other five keys can be given as
1293.Sy \&K1 ,
1294.Sy \&K2 ,
1295.Sy \&K3 ,
1296.Sy \&K4 ,
1297and
1298.Sy \&K5 .
1299These keys are useful when the effects of a 3 by 3 directional pad are needed.
1300The obsolete
1301.Sy \&ko
1302capability formerly used to describe
1303.Dq other
1304function keys has been
1305completely supplanted by the above capabilities.
1306.Pp
1307The
1308.Sy \&ma
1309entry is also used to indicate arrow keys on terminals that have
1310single-character arrow keys.
1311It is obsolete but still in use in
1312version 2 of
1313.Sy \&vi
1314which must be run on some minicomputers due to
1315memory limitations.
1316This field is redundant with
1317.Sy \&kl ,
1318.Sy \&kr ,
1319.Sy \&ku ,
1320.Sy \&kd ,
1321and
1322.Sy \&kh .
1323It consists of groups of two characters.
1324In each group, the first character is what an arrow key sends, and the
1325second character is the corresponding
1326.Sy \&vi
1327command.
1328These commands are
1329.Ar h
1330for
1331.Sy \&kl ,
1332.Ar j
1333for
1334.Sy \&kd ,
1335.Ar k
1336for
1337.Sy \&ku ,
1338.Ar l
1339for
1340.Sy \&kr ,
1341and
1342.Ar H
1343for
1344.Sy \&kh .
1345For example, the Mime would have
1346.Dq Li ma=^Hh^Kj^Zk^Xl
1347indicating arrow keys left (^H), down (^K), up (^Z), and right (^X).
1348(There is no home key on the Mime.)
1349.Ss Tabs and Initialization
1350If the terminal needs to be in a special mode when running
1351a program that uses these capabilities,
1352the codes to enter and exit this mode can be given as
1353.Sy \&ti
1354and
1355.Sy \&te .
1356This arises, for example, from terminals like the Concept with more than
1357one page of memory.
1358If the terminal has only memory-relative cursor addressing and not
1359screen-relative cursor addressing,
1360a screen-sized window must be fixed into
1361the display for cursor addressing to work properly.
1362This is also used for the Tektronix 4025, where
1363.Sy \&ti
1364sets the command character to be the one used by
1365.Nm .
1366.Pp
1367Other capabilities
1368include
1369.Sy \&is ,
1370an initialization string for the terminal,
1371and
1372.Sy \&if ,
1373the name of a file containing long initialization strings.
1374These strings are expected to set the terminal into modes
1375consistent with the rest of the
1376.Nm
1377description.
1378They are normally sent to the terminal by the
1379.Xr tset 1
1380program each time the user logs in.
1381They will be printed in the following order:
1382.Sy \&is ;
1383setting tabs using
1384.Sy \&ct
1385and
1386.Sy \&st ;
1387and finally
1388.Sy \&if .
1389.Pf ( Xr terminfo 5
1390uses
1391.Sy \&i\&1-i2
1392instead of
1393.Sy \&is
1394and runs the program
1395.Sy \&iP
1396and prints
1397.Sy "\&i\&3"
1398after the other initializations.)
1399A pair of sequences that does a harder reset from a totally unknown state
1400can be analogously given as
1401.Sy \&rs
1402and
1403.Sy \&if .
1404These strings are output by the
1405.Xr reset 1
1406program, which is used when the terminal gets into a wedged state.
1407.Pf ( Xr terminfo 5
1408uses
1409.Sy "\&r1-r3"
1410instead of
1411.Sy \&rs . )
1412Commands are normally placed in
1413.Sy \&rs
1414and
1415.Sy \&rf
1416only if they produce annoying effects on the screen and are not necessary
1417when logging in.
1418For example, the command to set the VT100 into 80-column mode
1419would normally be part of
1420.Sy \&is ,
1421but it causes an annoying glitch of the screen and is not normally needed
1422since the terminal is usually already in 80-column mode.
1423.Pp
1424If the terminal has hardware tabs,
1425the command to advance to the next tab stop can be given as
1426.Sy \&ta
1427(usually
1428.Sy \&^I ) .
1429A
1430.Dq backtab
1431command which moves leftward to the previous tab stop
1432can be given as
1433.Sy \&bt .
1434By convention,
1435if the terminal driver modes indicate that tab stops are being expanded
1436by the computer rather than being sent to the terminal,
1437programs should not use
1438.Sy \&ta
1439or
1440.Sy \&bt
1441even if they are present,
1442since the user may not have the tab stops properly set.
1443If the terminal has hardware tabs that are initially set every
1444.Ar n
1445positions when the terminal is powered up, then the numeric parameter
1446.Sy \&it
1447is given, showing the number of positions between tab stops.
1448This is normally used by the
1449.Xr tset 1
1450command to determine whether to set the driver mode for hardware tab
1451expansion, and whether to set the tab stops.
1452If the terminal has tab stops that can be saved in nonvolatile memory, the
1453.Nm
1454description can assume that they are properly set.
1455.Pp
1456If there are commands to set and clear tab stops, they can be given as
1457.Sy \&ct
1458(clear all tab stops) and
1459.Sy \&st
1460(set a tab stop in the current column of every row).
1461If a more complex sequence is needed to set the tabs than can be
1462described by this, the sequence can be placed in
1463.Sy \&is
1464or
1465.Sy \&if .
1466.Ss Delays
1467Certain capabilities control padding in the terminal driver.
1468These are primarily needed by hardcopy terminals and are used by the
1469.Xr tset 1
1470program to set terminal driver modes appropriately.
1471Delays embedded in the capabilities
1472.Sy \&cr ,
1473.Sy \&sf ,
1474.Sy \&le ,
1475.Sy \&ff ,
1476and
1477.Sy \&ta
1478will cause the appropriate delay bits to be set in the terminal driver.
1479If
1480.Sy \&pb
1481(padding baud rate) is given, these values can be ignored at baud rates
1482below the value of
1483.Sy \&pb .
1484For
1485.Bx 4.2
1486.Xr tset 1 ,
1487the delays are given as numeric capabilities
1488.Sy \&dC ,
1489.Sy \&dN ,
1490.Sy \&dB ,
1491.Sy \&dF ,
1492and
1493.Sy \&dT
1494instead.
1495.Ss Miscellaneous
1496If the terminal requires other than a
1497.Dv NUL
1498(zero) character as a pad,
1499this can be given as
1500.Sy \&pc .
1501Only the first character of the
1502.Sy \&pc
1503string is used.
1504.Pp
1505If the terminal has commands to save and restore the position of the
1506cursor, give them as
1507.Sy \&sc
1508and
1509.Sy \&rc .
1510.Pp
1511If the terminal has an extra
1512.Dq status line
1513that is not normally used by
1514software, this fact can be indicated.
1515If the status line is viewed as an extra line below the bottom line,
1516then the capability
1517.Sy \&hs
1518should be given.
1519Special strings to go to a position in the status line and to return
1520from the status line can be given as
1521.Sy \&ts
1522and
1523.Sy \&fs .
1524.Pf ( Sy \&fs
1525must leave the cursor position in the same place that it was before
1526.Sy \&ts .
1527If necessary, the
1528.Sy \&sc
1529and
1530.Sy \&rc
1531strings can be included in
1532.Sy \&ts
1533and
1534.Sy \&fs
1535to get this effect.)
1536The capability
1537.Sy \&ts
1538takes one parameter, which is the column number of the status line
1539to which the cursor is to be moved.
1540If escape sequences and other special commands such as tab work while in
1541the status line, the flag
1542.Sy \&es
1543can be given.
1544A string that turns off the status line (or otherwise erases its contents)
1545should be given as
1546.Sy \&ds .
1547The status line is normally assumed to be the same width as the
1548rest of the screen, i.e.\&
1549.Sy \&co .
1550If the status line is a different width (possibly because the terminal
1551does not allow an entire line to be loaded), then its width in columns
1552can be indicated with the numeric parameter
1553.Sy \&ws .
1554.Pp
1555If the terminal can move up or down half a line, this can be
1556indicated with
1557.Sy \&hu
1558(half-line up) and
1559.Sy \&hd
1560(half-line down).
1561This is primarily useful for superscripts and subscripts on hardcopy
1562terminals.
1563If a hardcopy terminal can eject to the next page (form feed),
1564give this as
1565.Sy \&ff
1566(usually
1567.Sy \&^L ) .
1568.Pp
1569If there is a command to repeat a given character a given number of times
1570(to save time transmitting a large number of identical characters),
1571this can be indicated with the parameterized string
1572.Sy \&rp .
1573The first parameter is the character to be repeated and the second is
1574the number of times to repeat it.
1575(This is a
1576.Xr terminfo 5
1577feature that is unlikely to be supported by a program that uses
1578.Nm . )
1579.Pp
1580If the terminal has a settable command character, such as the
1581Tektronix 4025, this can be indicated with
1582.Sy \&CC .
1583A prototype command character is chosen which is used in all capabilities.
1584This character is given in the
1585.Sy \&CC
1586capability to identify it.
1587The following convention is supported on some
1588.Ux
1589systems:
1590The environment is to be searched for a
1591.Ev \&CC
1592variable,
1593and if found,
1594all occurrences of the prototype character are replaced by the character
1595in the environment variable.
1596This use of the
1597.Ev \&CC
1598environment variable
1599is a very bad idea, as it conflicts with
1600.Xr make 1 .
1601.Pp
1602Terminal descriptions that do not represent a specific kind of known
1603terminal, such as
1604.Em switch ,
1605.Em dialup ,
1606.Em patch ,
1607and
1608.Em network ,
1609should include the
1610.Sy \&gn
1611(generic) capability so that programs can complain that they do not know
1612how to talk to the terminal.
1613(This capability does not apply to
1614.Em virtual
1615terminal descriptions for which the escape sequences are known.)
1616.Pp
1617If the terminal uses xoff/xon
1618.Pq Tn DC3 Ns / Ns Tn DC1
1619handshaking for flow control, give
1620.Sy \&xo .
1621Padding information should still be included so that routines can make
1622better decisions about costs, but actual pad characters will not be
1623transmitted.
1624.Pp
1625If the terminal has a
1626.Dq meta key
1627which acts as a shift key, setting the
16288th bit of any character transmitted, then this fact can be indicated with
1629.Sy \&km .
1630Otherwise, software will assume that the 8th bit is parity and it will
1631usually be cleared.
1632If strings exist to turn this
1633.Dq meta mode
1634on and off, they can be given as
1635.Sy \&mm
1636and
1637.Sy \&mo .
1638.Pp
1639If the terminal has more lines of memory than will fit on the screen at once,
1640the number of lines of memory can be indicated with
1641.Sy \&lm .
1642An explicit value of 0 indicates that the number of lines is not fixed,
1643but that there is still more memory than fits on the screen.
1644.Pp
1645If the terminal is one of those supported by the
1646.Ux
1647system virtual
1648terminal protocol, the terminal number can be given as
1649.Sy \&vt .
1650.Pp
1651Media copy strings which control an auxiliary printer
1652connected to the terminal can be given as
1653.Sy \&ps :
1654print the contents of the screen;
1655.Sy \&pf :
1656turn off the printer; and
1657.Sy \&po :
1658turn on the printer.
1659When the printer is on, all text sent to the terminal will be sent to the
1660printer.
1661It is undefined whether the text is also displayed on the terminal screen
1662when the printer is on.
1663A variation
1664.Sy \&pO
1665takes one parameter and leaves the printer on for as many characters as the
1666value of the parameter, then turns the printer off.
1667The parameter should not exceed 255.
1668All text, including
1669.Sy \&pf ,
1670is transparently passed to the printer while
1671.Sy \&pO
1672is in effect.
1673.Pp
1674Strings to program function keys can be given as
1675.Sy \&pk ,
1676.Sy \&pl ,
1677and
1678.Sy \&px .
1679Each of these strings takes two parameters: the function key number
1680to program (from 0 to 9) and the string to program it with.
1681Function key numbers out of this range may program undefined keys
1682in a terminal-dependent manner.
1683The differences among the capabilities are that
1684.Sy \&pk
1685causes pressing the given key to be the same as the user typing the given
1686string;
1687.Sy \&pl
1688causes the string to be executed by the terminal in local mode;
1689and
1690.Sy \&px
1691causes the string to be transmitted to the computer.
1692Unfortunately, due to lack of a definition for string parameters in
1693.Nm ,
1694only
1695.Xr terminfo 5
1696supports these capabilities.
1697.Ss Glitches and Brain-damage
1698Hazeltine terminals, which do not allow `~' characters to be displayed,
1699should indicate
1700.Sy \&hz .
1701.Pp
1702The
1703.Sy \&nc
1704capability, now obsolete, formerly indicated Datamedia terminals,
1705which echo
1706.Sy \&\er \en
1707for
1708carriage return then ignore a following linefeed.
1709.Pp
1710Terminals that ignore a linefeed immediately after an
1711.Sy \&am
1712wrap, such as the Concept, should indicate
1713.Sy \&xn .
1714.Pp
1715If
1716.Sy \&ce
1717is required to get rid of standout
1718(instead of merely writing normal text on top of it),
1719.Sy \&xs
1720should be given.
1721.Pp
1722Teleray terminals, where tabs turn all characters moved over to blanks,
1723should indicate
1724.Sy \&xt
1725(destructive tabs).
1726This glitch is also taken to mean that it is not possible
1727to position the cursor on top of a \*(lqmagic cookie\*(rq, and that
1728to erase standout mode it is necessary to use delete and insert line.
1729.Pp
1730The Beehive Superbee, which is unable to correctly transmit the
1731.Dv ESC
1732or
1733.Sy \&^C
1734characters, has
1735.Sy \&xb ,
1736indicating that the
1737.Dq \&f\&1
1738key is used for
1739.Dv ESC
1740and
1741.Dq \&f\&2
1742for ^C.
1743(Only certain Superbees have this problem, depending on the
1744.Tn ROM . )
1745.Pp
1746Other specific terminal problems may be corrected by adding more
1747capabilities of the form
1748.Sy x Em x .
1749.Ss Similar Terminals
1750If there are two very similar terminals,
1751one can be defined as being just like the other with certain exceptions.
1752The string capability
1753.Sy \&tc
1754can be given
1755with the name of the similar terminal.
1756This capability must be
1757.Em last ,
1758and the combined length of the entries
1759must not exceed 1024.
1760The capabilities given before
1761.Sy \&tc
1762override those in the terminal type invoked by
1763.Sy \&tc .
1764A capability can be cancelled by placing
1765.Sy \&xx@
1766to the left of the
1767.Sy \&tc
1768invocation, where
1769.Sy \&xx
1770is the capability.
1771For example, the entry
1772.Bd -literal -offset indent
1773hn\||\|2621\-nl:ks@:ke@:tc=2621:
1774.Ed
1775.Pp
1776defines a
1777.Dq 2621\-nl
1778that does not have the
1779.Sy \&ks
1780or
1781.Sy \&ke
1782capabilities,
1783hence does not turn on the function key labels when in visual mode.
1784This is useful for different modes for a terminal, or for different
1785user preferences.
1786.Sh FILES
1787.Bl -tag -width /usr/share/misc/termcap.db -compact
1788.It Pa /usr/share/misc/termcap
1789File containing terminal descriptions.
1790.It Pa /usr/share/misc/termcap.db
1791Hash database file containing terminal descriptions (see
1792.Xr cap_mkdb 1 ) .
1793.El
1794.Sh SEE ALSO
1795.Xr cap_mkdb 1 ,
1796.Xr ex 1 ,
1797.Xr more 1 ,
1798.Xr tset 1 ,
1799.Xr ul 1 ,
1800.Xr vi 1 ,
1801.Xr curses 3 ,
1802.Xr printf 3 ,
1803.Xr termcap 3 ,
1804.Xr terminfo 3 ,
1805.Xr terminfo 5 ,
1806.Xr term 7
1807.Sh HISTORY
1808The
1809.Nm
1810file format appeared in
1811.Bx 3 .
1812.Sh CAVEATS
1813The
1814.Nm
1815functions
1816were replaced by
1817.Xr terminfo 5
1818in
1819.At V
1820Release 2.0.
1821The transition will be relatively painless if capabilities flagged as
1822.Dq obsolete
1823are avoided.
1824.Sh BUGS
1825Lines and columns are now stored by the kernel as well as in the termcap
1826entry.
1827Most programs now use the kernel information primarily; the information
1828in this file is used only if the kernel does not have any information.
1829.Pp
1830Historically, the total length of a single entry (excluding only
1831escaped newlines) was limited to 1023 bytes, not including the NUL
1832terminator.
1833Larger entries may lead to a buffer overflow on some systems.
1834.Pp
1835Not all programs support all entries.
1836