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## 5. Feature Descriptions

## 5.1 Cursor Routing

When moving the braille window around the screen while examining the text, say, in an editor, you often need to bring the cursor to a specific character within the braille window. You'll probably find this to be a rather difficult task for a number of reasons. One is that you may not know where the cursor is, and that you may lose your place while trying to find it. Another is that the cursor may move unrpedictably as the arrow keys are pressed (some editors, for example, don't allow the cursor to be more to the right than the end of the line it's on). Cursor routing provides just such a capability by knowing where the cursor is, by simulating the same arrow-key presses which you'd have to enter manually, and by monitoring the progress of the cursor as it moves.

Some braille displays have a button, known as a routing key, above each cell. These keys use the ROUTE command to route the cursor right to the desired location.

Cursor routing, while very convenient and effective, is, strictly speaking, not completely reliable. One reason for this is that its current implementation assumes VT100 cursor key escape sequences. Another is that some applications do non-standard things in response to detecting that a cursor key has been pressed. A minor problem found within some editors (like `vi`), as already mentioned above, is that they throw in some unpredictable horizontal motion when vertical motion is requested because they don't allow the cursor to be to the right of the end of a line. A major problem found within some web browsers (like `lynx`) is that the up- and down-arrow keys are used to move among the links (which may skip lines and/or move the cursor horizontally, but which rarely just moves the cursor one line in the desired direction), and that the left- and right-arrow keys are used to select links (which has absolutely nothing to do with any form of cursor motion whatsoever, and which even totally changes the screen content).

Cursor routing may not work very well on a heavily loaded system, and definitely doesn't work very well when working on a remote system over a slow link. This is so because of all of the checks which must be made along the way in order to deal with unpredictable cursor motion and in order to ensure that any mistake has at least a fighting chance to be undone. Even though BRLTTY tries to be fairly clever, it must still essentially wait to see what happens after each simulated arrow-key press.

Once a cursor routing request has been made, BRLTTY keeps trying to route the cursor to the desired location until a timeout expires before the cursor reaches that location, the cursor seems to be moving in the wrong direction, or you switch to a different virtual terminal. An attempt is first made to use virtical motion to bring the cursor to the right line, and, only if that succeeds, an attempt is then made to use horizontal motion to bring the cursor to the right column. If another request is made while one is still in progress, then the first one is aborted and the second one is initiated.

A safer but less powerful cursor routing command, CSRJMP_VERT, uses just vertical motion to bring the cursor to anywhere on the top line of the braille window. It's especially useful in conjunction with applications (like `lynx`) wherein horizontal cursor motion must never be attempted.

## 5.2 Cut and Paste

This feature enables you to grab some text which is already on the screen and re-enter it at the current cursor position. Using it saves time and avoids errors when a long and/or complicated piece of text needs to be copied, and even when the same short and simple piece of text needs to be copied many times. It's particularly useful for things like long file names, complicated command lines, E-mail addresses, and URLs. Cutting and pasting text involves three simple steps:

1. Mark either the top-left corner of the rectangular area or the beginning of the linear area on the screen which is to be grabbed (cut). If your display has routing keys, then move the braille window so that the first character to be cut appears anywhere within it, and then:
   - invoke the CUTBEGIN command to start a new cut buffer
   - invoke the CUTAPPEND command to append to the existing cut buffer
   by pressing the key(s) associated with it and then pressing the routing key associated with the character.
2. Mark either the bottom-right corner of the rectangular area or the end of the linear area on the screen which is to be grabbed (cut). If your display has routing keys, then move the braille window so that the last character to be cut appears anywhere within it, and then
   - invoke the CUTRECT command to cut a rectangular area
   - invoke the CUTLINE command to cut a linear area
   by pressing the key(s) associated with it and then pressing the routing key associated with the character. Marking the end of the cut area appends the selected screen content to the cut buffer. Excess white-space is removed from the end of each line in the cut buffer so that unwanted trailing spaces won't be pasted back in. Control characters are replaced with blanks.
3. Insert (paste) the text where it's needed. Place the cursor over the character where the text is to be pasted, and invoke the PASTE command. You can paste the same text any number of times without recutting it. This description assumes that you're already in some sort of input mode. If you paste when you're in some other kind of mode (like `vi`'s command mode), then you'd better be aware of what the characters in the cut buffer will do.

The cut buffer is also used by the PRSEARCH/NXSEARCH commands.

## 5.3 Pointer (Mouse) Support via GPM

If BRLTTY is configured with the --enable-gpm build option on a system where the `gpm` application has been installed, then it'll interact with the pointer (mouse).

Moving the pointer drags the braille window (see the Window Follows Pointer preference). Whenever the pointer is moved beyond the edge of the braille window, the braille window is dragged along (one character at a time). This gives the braille user another two-dimensional way to inspect the screen content or to quickly move the braille window to a desired location. It also gives a sighted observer an easy way to move the braille window to something he'd like the braille user to read.

`gpm` uses reverse video to show where the pointer is. Underlining of highlighted characters (see the ATTRVIS command for details) should be turned on, therefore, when the braille user wishes to use the pointer.

This feature also gives the braille user access to `gpm`'s cut-and-paste capability. Although you should read `gpm`'s own documentation, here are some notes on how it works.

- Copy the current character to the cut buffer by single-clicking the left button.
- Copy the current word (space-delimited) to the cut buffer by double-clicking the left button.
- Copy the current line to the cut buffer by tripple-clicking the left button.
- Copy a linear region to the cut buffer as follows:
  1. Place the pointer on the first character of the region.
  2. Press (and hold) the left button.
  3. Move the pointer to the last character of the region (all currently selected characters are highlighted).
  4. Release the left button.
- Paste (input) the current contents of the cut buffer by clicking the middle button of a three-button mouse or by clicking the right button of a two-button mouse.
- Append to the cut buffer by using the right button of a three-button mouse.

## 5.4 Alert Tunes

BRLTTY alerts you to the occurrence of significant events by playing short predefined tunes. This feature can be activated and deactivated with either the TUNES command or the Alert Tunes preference. The tunes are played via the internal beeper by default, but other alternatives can be selected with the Tune Device preference.

Each significant event is associated, from highest to lowest priority, with one or more of the following:

a tune

  If a tune has been associated with the event, if the Alert Tunes preference (see also the TUNES command) is active, and if the selected tune device (see the Tune Device preference) can be opened, then the tune is played.

a dot pattern

  If a dot pattern has been associated with the event, and if the Alert Dots preference is active, then the dot pattern is briefly displayed on every braille cell. Some braille displays don't respond quickly enough for this mechanism to work effectively.

a message

  If a message has been associated with the event, and if the Alert Messages preference is active, then it is displayed for a few seconds (see the -M command line option).

These events include:

- When the braille display driver starts or stops.
- When a lengthy command completes.
- When a command cannot be executed.
- When a mark is set.
- When the start or end of the cut block is set.
- When a feature is activated or deactivated.
- When cursor tracking is turned on or off.
- When the screen image is frozen or unfrozen.
- When the braille window wraps either down to the beginning of the next line or up to the end of the previous line.
- When identical lines are skipped.
- When a requested motion cannot be performed.
- When cursor routing starts, finishes, or fails.

## 5.5 Preferences Settings

When BRLTTY starts, it loads a file which contains your preferences settings. The file doesn't need to exist, and is created the first time the settings are saved with the PREFSAVE command. The most recently saved settings can be restored at any time with the PREFLOAD command.

The name for this file is `/etc/brltty-`driver`.prefs`. where driver is the two-letter driver identification code.

### The Preferences Menu

The preferences settings are saved as binary data which, therefore, can't be edited by hand. BRLTTY, however, has a simple menu from which you can easily change them. This feature isn't available if the --disable-preferences-menu build option was specified.

The meny is activated by the PREFMENU command. The braille display briefly (see the -M command line option) shows the menu title, and then presents the current item and its current setting.

### Navigating the Menu

See Menu Navigation Commands for the full list of commands which enable you to select items and change settings within the menu. For backward compatibility with old drivers, the window motion commands, which have modified meanings in this context, can also be used.

`TOP`/`BOT`, `TOP_LEFT`/`BOT_LEFT`, `PAGE_UP`/`PAGE_DOWN`

  Go to the first/last item in the menu (same as MENU_FIRST_ITEM/MENU_LAST_ITEM).

`LNUP`/`LNDN`, `PRDIFLN`/`NXDIFLN`, `CURSOR_UP`/`CURSOR_DOWN`

  Go to the previous/next item in the menu (same as MENU_PREV_ITEM/MENU_NEXT_ITEM).

`WINUP`/`WINDN`, `CHRLT`/`CHRRT`, `CURSOR_LEFT`/`CURSOR_RIGHT`, `BACK`/`HOME`

  Decrement/increment the current menu item's setting (same as MENU_PREV_SETTING/MENU_NEXT_SETTING).

Notes:

- The routing keys can also be used to select a setting for the current item. If the item has numeric settings, then the entire row of routing keys acts as a scroll bar which covers the full range of valid values. If the item has named settings, then the routing keys correspond ordinally with the settings.
- Use the `PREFLOAD` command to undo all of the changes which were made since entering the menu.
- Use the `PREFMENU` command (again) to leave the new settings in effect, exit the menu, and resume normal operation. If the "Save Settings on Exit" item is set, then, in addition, the new settings are written to the preferences settings file. Any command not recognized by the menu system also does these same things.

### The Menu Items

Save on Exit

  When exiting the preferences menu:

  No

    Don't automatically save the preferences settings.

  Yes

    Automatically save the preferences settings.

  The initial setting is `No`.
Text Style

  When displaying screen content (see the DISPMD command), show characters:

  8-dot

    With all eight dots.

  6-dot

    With only dots 1 through 6. If a contraction table has been selected (see the -c command line option and the contraction-table configuration file directive), then it is used.

  This setting can also be changed with the SIXDOTS command.
Skip Identical Lines

  When moving either up or down exactly one line with the LNUP/LNDN commands, as well as the line wrapping feature of the FWINLT/FWINRT and FWINLTSKIP/FWINRTSKIP commands:

  No

    Don't skip past lines which have the same content as the current line.

  Yes

    Skip past lines which have the same content as the current line.

  This setting can also be changed with the SKPIDLNS command.
Skip Blank Windows

  When moving either left or right with the FWINLT/FWINRT commands:

  No

    Don't skip past blank windows.

  Yes

    Skip past blank windows.

  This setting can also be changed with the SKPBLNKWINS command.
Which Blank Windows

  If blank windows are to be skipped:

  All

    Skip all of them.

  End of Line

    Only skip those which are at the end (on the right side) of a line.

  Rest of Line

    Only skip those which are at the end (on the right side) of a line when reading forward, and at the beginning (on the left side) of a line when reading backward.

Sliding Window

  If the cursor is being tracked (see the CSRTRK command), and the cursor moves too close to (or beyond) either end of the braille window:

  No

    Horizontally reposition the window such that its left end is a multiple of its width from the left edge of the screen.

  Yes

    Horizontally reposition the window such that the cursor, while remaining on that side of the window, is nearer the centre.

  This setting can also be changed with the SLIDEWIN command.
Eager Sliding Window

  If the braille window is to slide:

  No

    Reposition it whenever the cursor moves beyond either end.

  Yes

    Reposition it whenever the cursor moves too close to either end.

  The initial setting is `No`.
Window Overlap

  When moving either left or right with the FWINLT/FWINRT commands, this setting specifies how many characters horizontally adjacent braille windows should overlap each other by. The initial setting is `0`.

Autorepeat

  While the key (combination) for a command remains pressed:

  No

    Don't automatically repeat the command.

  Yes

    Automatically repeat the command at a regular interval after an initial delay.

  The following commands are eligible for autorepeating:
  - The LNUP/LNDN commands.
  - The PRDIFLN/NXDIFLN commands.
  - The CHRLT/CHRRT commands.
  - Braille window panning operations (see the Autorepeat Panning preference).
  - The Page-Up and Page-Down operations.
  - The Cursor-Up and Cursor-Down operations.
  - The Cursor-Left and Cursor-Right operations.
  - The Backspace and Delete operations.
  - Character entry.
  Only some drivers support this functionality, the primary limitation being that many braille displays don't signal both key presses and key releases as distinctly separate events. This setting can also be changed with the AUTOREPEAT command. The initial setting is `Yes`.
Autorepeat Panning

  When the Autorepeat preference is enabled:

  No

    Don't autorepeat braille window panning operations.

  Yes

    Autorepeat braille window panning operations.

  This preference affects the FWINLT/FWINRT commands. The initial setting is `No`.
Autorepeat Delay

  When a character is to be autorepeated, this setting specifies the amount of time (see the note on time settings below) which must pass before autorepeating begins. The initial setting is `50`.

Autorepeat Interval

  When a character is being autorepeated, this setting specifies the amount of time (see the note on time settings below) between each reexecution. The initial setting is `10`.

Show Cursor

  When displaying screen content (see the DISPMD command):

  No

    Don't show the cursor.

  Yes

    Show the cursor.

  This setting can also be changed with the CSRVIS command. The initial setting is `Yes`.
Cursor Style

  When showing the cursor, represent it:

  Underline

    With dots 7 and 8.

  Block

    With all eight dots.

  This setting can also be changed with the CSRSIZE command.
Blinking Cursor

  When the cursor is to be shown:

  No

    Leave it visible all the time.

  Yes

    Make it alternately visible and invisible according to a predefined interval.

  This setting can also be changed with the CSRBLINK command.
Cursor Visible Time

  When the cursor is to be blinked, this setting specifies the length of time (see the note on time settings below) during each cycle that it is to be visible. The initial setting is `40`.

Cursor Invisible Time

  When the cursor is to be blinked, this setting specifies the length of time (see the note on time settings below) during each cycle that it is to be invisible. The initial setting is `40`.

Show Attributes

  When displaying screen content (see the DISPMD command):

  No

    Don't underline highlighted characters.

  Yes

    Underline highlighted characters.

  This setting can also be changed with the ATTRVIS command.
Blinking Attributes

  When highlighted characters are to be underlined:

  No

    Leave the indicator visible all the time.

  Yes

    Make the indicator alternately visible and invisible according to a predefined interval.

  This setting can also be changed with the ATTRBLINK command.
Attributes Visible Time

  When the highlighted character underline is to be blinked, this setting specifies the length of time (see the note on time settings below) during each cycle that it is to be visible. The initial setting is `20`.

Attributes Invisible Time

  When the highlighted character underline is to be blinked, this setting specifies the length of time (see the note on time settings below) during each cycle that it is to be invisible. The initial setting is `60`.

Blinking Capitals

  When displaying screen content (see the DISPMD command):

  No

    Leave capital letters visible all the time.

  Yes

    Make capital letters alternately visible and invisible according to a predefined interval.

  This setting can also be changed with the CAPBLINK command.
Capitals Visible Time

  When capital letters are to be blinked, this setting specifies the length of time (see the note on time settings below) during each cycle that they're to be visible. The initial setting is `60`.

Capitals Invisible Time

  When capital letters are to be blinked, this setting specifies the length of time (see the note on time settings below) during each cycle that they're to be invisible. The initial setting is `20`.

Braille Firmness

  Adjust the firmness (or stiffness) of the braille dots. It can be set to:

  - Maximum
  - High
  - Medium
  - Low
  - Minimum
  This preference is only available if a driver which supports it is being used. The initial setting is `Medium`.
Braille Sensitivity

  Adjust the sensitivity of the braille dots to touch. It can be set to:

  - Maximum
  - High
  - Medium
  - Low
  - Minimum
  This preference is only available if a driver which supports it is being used. The initial setting is `Medium`.
Window Follows Pointer

  When moving the pointer device (mouse):

  No

    Don't drag the braille window.

  Yes

    Drag the braille window.

  This preference is only presented if the --enable-gpm build option was specified.
Highlight Window

  When moving the braille window:

  No

    Don't highlight the new screen area.

  Yes

    Highlight the new screen area.

  This feature enables a sighted observer to see where the braille window is, and, therefore, to know what the braille user is reading. Any motion of the braille window (manual, cursor tracking, etc.), other than when it moves in response to pointer (mouse) motion (see the Window Follows Pointer preference), causes the area of the screen corresponding to the new location of the braille window to be highlighted. If the Show Attributes preference is enabled then only the character corresponding to the upper-left corner of the braille window is highlighted.
Alert Tunes

  Whenever a significant event with an associated tune occurs (see Alert Tunes):

  No

    Don't play the tune.

  Yes

    Play the tune.

  This setting can also be changed with the TUNES command. The initial setting is `Yes`.
Tune Device

  Play alert tunes via:

  Beeper

    The internal beeper (console tone generator). This setting is supported on Linux, on OpenBSD, on FreeBSD, and on NetBSD. It's always safe to use, although it may be somewhat soft. This device isn't available if the --disable-beeper-support build option was specified.

  PCM

    The digital audio interface on the sound card. This setting is supported on Linux (via `/dev/dsp`), on Solaris (via `/dev/audio`), on OpenBSD (via `/dev/audio0`), on FreeBSD (via `/dev/dsp`), and on NetBSD (via `/dev/audio0`). It doesn't work when this device is already being used by another application. This device isn't available if the --disable-pcm-support build option was specified.

  MIDI

    The Musical Instrument Digital Interface on the sound card This setting is supported on Linux (via `/dev/sequencer`). It doesn't work when this device is already being used by another application. This device isn't available if the --disable-midi-support build option was specified.

  FM

    The FM synthesizer on an AdLib, OPL3, Sound Blaster, or equivalent sound card. This setting is supported on Linux. It works even if the FM synthesizer is already being used by another application. The results are unpredictable, and potentially not very good, if it's used with a sound card which doesn't support this feature. This device isn't available if the --disable-fm-support build option was specified.

  The initial setting is `Beeper` on those platforms which support it, and `PCM` on those platforms which don't.
PCM Volume

  If the digital audio interface of the sound card is being used to play the alert tunes, this setting specifies the loudness (as a percentage of the maximum) at which they are to be played. The initial setting is `70`.

MIDI Volume

  If the Musical Instrument Digital Interface (MIDI) of the sound card is being used to play the alert tunes, this setting specifies the loudness (as a percentage of the maximum) at which they are to be played. The initial setting is `70`.

MIDI Instrument

  If the Musical Instrument Digital Interface (MIDI) of the sound card is being used to play the alert tunes, this setting specifies which instrument is to be used (see the MIDI Instrument Table). The initial setting is `Acoustic Grand Piano`.

FM Volume

  If the FM synthesizer of the sound card is being used to play the alert tunes, this setting specifies the loudness (as a percentage of the maximum) at which they are to be played. The initial setting is `70`.

Alert Dots

  Whenever a significant event with an associated dot pattern occurs (see Alert Tunes):

  No

    Don't display the dot pattern.

  Yes

    Briefly display the dot pattern.

  If alert tunes are to be played (see the TUNES command and the Alert Tunes preference), if a tune has been associated with the event, and if the selected tune device can be opened, then, regardless of the setting of this preference, the dot pattern isn't displayed.
Alert Messages

  Whenever a significant event with an associated message occurs (see Alert Tunes):

  No

    Don't display the message.

  Yes

    Display the message.

  If alert tunes are to be played (see the TUNES command and the Alert Tunes preference), if a tune has been associated with the event, and if the selected tune device can be opened, or if alert dot patterns are to be displayed (see the Alert Dots preference) and if a dot pattern has been associated with the event, then, regardless of the setting of this preference, the message isn't displayed.
Say-Line Mode

  When using the SAY_LINE command:

  Immediate

    Discard pending speech.

  Enqueue

    Don't discard pending speech.

  The initial setting is `Immediate`.
Autospeak

  No

    Only speak when explicitly requested to do so.

  Yes

    Automatically speak:

    - the new line when the braille window is moved vertically.
    - characters which are entered or deleted.
    - the character to which the cursor is moved.
  This setting can also be changed with the AUTOSPEAK command. The initial setting is `No`.
Speech Rate

  Adjust the speech rate (`0` is the slowest, `20` is the fastest). This preference is only available if a driver which supports it is being used. This setting can also be changed with the SAY_SLOWER/SAY_FASTER commands. The initial setting is `10`.

Speech Volume

  Adjust the speech volume (`0` is the softest, `20` is the loudest). This preference is only available if a driver which supports it is being used. This setting can also be changed with the SAY_SOFTER/SAY_LOUDER commands. The initial setting is `10`.

Speech Pitch

  Adjust the speech pitch (`0` is the lowest, `20` is the highest). This preference is only available if a driver which supports it is being used. The initial setting is `10`.

Speech Punctuation

  Adjust the amount of punctuation which is spoken. It can be set to:

  - All
  - Some
  - All
  This preference is only available if a driver which supports it is being used. The initial setting is `Some`.
Status Style

  This setting specifies the way that the status cells are to be used. You shuldn't normally need to play with it. It enables BRLTTY's developers to test status cell configurations for braille displays which they don't actually have.

  None

    Don't use the status cells. This setting is always safe, but it's also quite useless.

  Alva

    The status cells contain:

    1

      The location of the cursor (see below).

    2

      The location of the top-left corner of the braille window (see below).

    3

      A letter indicating BRLTTY's state. In order of precedence:

      a

        Screen attributes are being shown (see the DISPMD command).

      f

        The screen image is frozen (see the FREEZE command).

      f

        The cursor is being tracked (see the CSRTRK command).

      blank

        Nothing special.

    The locations of the cursor and the braille window are presented in an interesting way. Dots 1 through 6 represent the line number with a letter from `a` (for 1) through `y` (for 25). Dots 7 and 8 (the extra two at the bottom) represent the horizontal braille window number as follows:
    No Dots

      The first (leftmost) window.

    Dot 7

      The second window.

    Dot 8

      The third window.

    Dots 7 and 8

      The fourth window.

    In both cases, the indicators wrap: line 26 is represented by the letter `a`, and the fifth horizontal braille window is represented by no dots at the bottom.
  Tieman

    The status cells contain:

    1-2

      The columns (counting from 1) of the cursor (shown in the top half of the cells) and the top-left corner of the braille window (shown in the bottom half of the cells).

    3-4

      The rows (counting from 1) of the cursor (shown in the top half of the cells) and the top-left corner of the braille window (shown in the bottom half of the cells).

    5

      Each dot indicates if a feature is turned on as follows:

      Dot 1

        The screen image is frozen (see the FREEZE command).

      Dot 2

        Screen attributes are being displayed (see the DISPMD command).

      Dot 3

        Alert tunes are being played (see the TUNES command).

      Dot 4

        The cursor is being shown (see the CSRVIS command).

      Dot 5

        The cursor is a solid block (see the CSRSIZE command).

      Dot 6

        The cursor is blinking (see the CSRBLINK command).

      Dot 7

        The cursor is being tracked (see the CSRTRK command).

      Dot 8

        The braille window will slide (see the SLIDEWIN command).

  PowerBraille 80

    The status cells contain:

    1

      The row (counting from 1) corresponding to the top of the braille window. The tens digit is shown in the top half of the cell, and the units digit is shown in the bottom half of the cell.

  Generic

    This setting passes a lot of information to the braille driver, and the driver itself decides how to present it.

  MDV

    The status cells contain:

    1-2

      The location of the top-left corner of the braille window. The row (counting from 1) is shown in the top half of the cells, and the column (counting from 1) is shown in the bottom half of the cells.

  Voyager

    The status cells contain:

    1

      The row (counting from 1) corresponding to the top of the braille window (see below).

    2

      The row (counting from 1) whereon the cursor is (see below).

    3

      If the screen is frozen (see the FREEZE command), then the letter `F`. If it isn't, then the column (counting from 1) wherein the cursor is (see below).

    Row and column numbers are shown as two digits within a single cell. The tens digit is shown in the top half of the cell, and the units digit is shown in the bottom half of the cell.
  The initial setting is braille display driver dependent.
Text Table

  Select the text translation table. See section Text Translation for details. See the -t command line option for the initial setting. This preference isn't saved. It isn't presented if the --disable-table-selection build option was specified.

Attributesw Table

  Select the attributes translation table. See section Attributes Translation for details. See the -a command line option for the initial setting. This preference isn't saved. It isn't presented if the --disable-table-selection build option was specified.

Contraction Table

  Select the contraction table. See section Contracted Braille for details. See the -c command line option for the initial setting. This preference isn't saved. It isn't presented if the --disable-table-selection build option was specified.

Notes:

- All time settings are in hundredths of a second. They are multiples of the braille window update interval (see the -U command line option) within the range 1 through 100.

## 5.6 The Status Display

The status display is a summary of BRLTTY's current state which fits completely within the braille window. Some braille displays have a set of status cells which are used to permanently display some of this information as well (see the documentation for your display's driver). The data presented by this display isn't static, and may change at any time in response to screen updates and/or BRLTTY commands.

Use the INFO command to switch to the status display, and use it again to return to the screen. The layout of the information contained therein is dependent on the size of the braille window.

### Displays with 21 Cells or More

Short pneumonics have been used, even though they're rather cryptic, in order to show the precise column layout.

> `wx:wy cx:cy vt tcmfdu`

wx`:`wy

  The column and row (counting from 1) on the screen corresponding to the top-left corner of the braille window.

cx`:`cy

  The column and row (counting from 1) on the screen corresponding to the position of the cursor.

vt

  The number (counting from 1) of the current virtual terminal.

t

  The state of the cursor tracking feature (see the CSRTRK command).

  blank

    Cursor tracking is off.

  `t`

    Cursor tracking is on.

c

  The state of the cursor visibility features (see the CSRVIS and CSRBLINK commands).

  blank

    The cursor isn't visible, and won't blink when made visible.

  `b`

    The cursor isn't visible, and will blink when made visible.

  `v`

    The cursor is visible, and isn't blinking.

  `B`

    The cursor is visible, and is blinking.

m

  The current display mode (see the DISPMD command).

  `t`

    Screen content (text) is being displayed.

  `a`

    Screen highlighting (attributes) is being displayed.

f

  The state of the frozen screen feature (see the FREEZE command).

  blank

    The screen isn't frozen.

  `f`

    The screen is frozen.

d

  The number of braille dots being used to display each character (see the SIXDOTS command).

  `8`

    All eight dots are being used.

  `6`

    Only dots 1 through 6 are being used.

u

  The state of the uppercase (capital letter) display features (see the CAPBLINK command).

  blank

    Uppercase letters don't blink.

  `B`

    Uppercase letters blink.

### Displays with 20 Cells or Less

Short pneumonics have been used, even though they're rather cryptic, in order to show the precise column layout.

> `xxyys vt tcmfdu`

xx

  The columns (counting from 1) on the screen corresponding to the position of the cursor (shown in the top half of the cells) and to the top-left corner of the braille window (shown in the bottom half of the cells).

yy

  The rows (counting from 1) on the screen corresponding to the position of the cursor (shown in the top half of the cells) and to the top-left corner of the braille window (shown in the bottom half of the cells).

s

  The settings of some of BRLTTY's features. A feature is turned on if its corresponding dot is raised.

  Dot 1

    Frozen screen image (see the FREEZE command).

  Dot 2

    Display attributes (see the DISPMD command).

  Dot 3

    Alert tunes (see the TUNES command).

  Dot 4

    Visible cursor (see the CSRVIS command).

  Dot 5

    Block cursor (see the CSRSIZE command).

  Dot 6

    Blinking cursor (see the CSRBLINK command).

  Dot 7

    Cursor tracking (see the CSRTRK command).

  Dot 8

    Sliding window (see the SLIDEWIN command).

vt

  The number (counting from 1) of the current virtual terminal.

t

  The state of the cursor tracking feature (see the CSRTRK command).

  blank

    Cursor tracking is off.

  `t`

    Cursor tracking is on.

c

  The state of the cursor visibility features (see the CSRVIS and CSRBLINK commands).

  blank

    The cursor isn't visible, and won't blink when made visible.

  `b`

    The cursor isn't visible, and will blink when made visible.

  `v`

    The cursor is visible, and isn't blinking.

  `B`

    The cursor is visible, and is blinking.

m

  The current display mode (see the DISPMD command).

  `t`

    Screen content (text) is being displayed.

  `a`

    Screen highlighting (attributes) is being displayed.

f

  The state of the frozen screen feature (see the FREEZE command).

  blank

    The screen isn't frozen.

  `f`

    The screen is frozen.

d

  The number of braille dots being used to display each character (see the SIXDOTS command).

  `8`

    All eight dots are being used.

  `6`

    Only dots 1 through 6 are being used.

u

  The state of the uppercase (capital letter) display features (see the CAPBLINK command).

  blank

    Uppercase letters don't blink.

  `B`

    Uppercase letters blink.

## 5.7 Command Learn Mode

Command learn mode is an interactive way to learn what the keys on the braille display do. It can be accessed either by the LEARN command or via the brltest utility. This feature isn't available if the --disable-learn-mode build option was specified.

When this mode is entered, the message `command learn mode` is written to the braille display. Then, as each key (or key combination) on the display is pressed, a short message describing its BRLTTY function is written. This mode exits immediately if the key (or key combination) for the LEARN command is pressed. It exits automatically, and the message `done` is written, if ten seconds elapse without any key on the display being pressed. Note that some displays don't signal the driver and/or some drivers don't signal BRLTTY until all the keys are released.

If a message is longer than the braille display is wide, then it's displayed in segments. The length of each segment but the last is one less than the display's width, with the rightmost character on the display being set to a minus sign. Each such segment remains on the display either for a few seconds (see the -M command line option) or until any key on the display is pressed.

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