+.SH ENVIRONMENT
+The following environment symbols are useful for customizing the
+runtime behavior of the \fBncurses\fR library. The most important
+ones have been already discussed in detail.
+.TP 5
+BAUDRATE
+The debugging library checks this environment symbol when the application
+has redirected output to a file.
+The symbol's numeric value is used for the baudrate.
+If no value is found \fBncurses\fR uses 9600.
+This allows testers to construct repeatable test-cases
+that take into account costs that depend on baudrate.
+.TP 5
+CC
+When set, change occurrences of the command_character
+(i.e., the \fBcmdch\fP capability)
+of the loaded terminfo entries to the value of this symbol.
+Very few terminfo entries provide this feature.
+.TP 5
+COLUMNS
+Specify the width of the screen in characters.
+Applications running in a windowing environment usually are able to
+obtain the width of the window in which they are executing.
+If neither the $COLUMNS value nor the terminal's screen size is available,
+\fBncurses\fR uses the size which may be specified in the terminfo database
+(i.e., the \fBcols\fR capability).
+
+It is important that your application use a correct size for the screen.
+However, this is not always possible because your application may be
+running on a host which does not honor NAWS (Negotiations About Window
+Size), or because you are temporarily running as another user.
+
+Either COLUMNS or LINES symbols may be specified independently.
+This is mainly useful to circumvent legacy misfeatures of terminal descriptions,
+e.g., xterm which commonly specifies a 65 line screen.
+For best results, \fBlines\fR and \fBcols\fR should not be specified in
+a terminal description for terminals which are run as emulations.
+
+Use the \fBuse_env\fR function to disable this feature.
+.TP 5
+DISPLAY
+Provides a hint to ncurses that your terminal is an X terminal
+emulator such as \fBxterm\fP.
+If the \fBkmous\fP capability is set to the beginning of the xterm
+mouse response, e.g., "kmous=\E[M", then ncurses will send the terminal
+xterm's mouse initialization strings and allow appropriate replies.
+See the \fBcurs_mouse\fR(3X) manual page for programming information.
+.TP 5
+ESCDELAY
+Specifies the total time, in milliseconds, for which ncurses will
+await a character sequence, e.g., a function key.
+The default value, 1000 milliseconds, is enough for most uses.
+However, it is made a variable to accommodate unusual applications.
+
+The most common instance where you may wish to change this value
+is to work with slow hosts, e.g., running on a network.
+If the host cannot read characters rapidly enough, it will have the same
+effect as if the terminal did not send characters rapidly enough.
+The library will still see a timeout.
+
+Note that xterm mouse events are built up from character sequences
+received from the xterm.
+If your application makes heavy use of multiple-clicking, you may
+wish to lengthen this default value because the timeout applies
+to the composed multi-click event as well as the individual clicks.
+.TP 5
+HOME
+Tells \fBncurses\fR where your home directory is.
+That is where it may read and write auxiliary terminal descriptions:
+
+$HOME/.termcap
+.br
+$HOME/.terminfo
+.TP 5
+LINES
+Like COLUMNS, specify the height of the screen in characters.
+See COLUMNS for a detailed description.
+.TP 5
+MOUSE_BUTTONS_123
+This applies only to the OS/2 EMX port.
+It specifies the order of buttons on the mouse.
+OS/2 numbers a 3-button mouse inconsistently from other
+platforms:
+
+1 = left
+.br
+2 = right
+.br
+3 = middle.
+
+This symbol lets you customize the mouse.
+The symbol must be three numeric digits 1-3 in any order, e.g., 123 or 321.
+If it is not specified, \fBncurses\fR uses 132.
+.TP 5
+NCURSES_NO_PADDING
+Most of the terminal descriptions in the terminfo database are written
+for real "hardware" terminals.
+Many people use terminal emulators
+which run in a windowing environment and use curses-based applications.
+Terminal emulators can duplicate
+all of the important aspects of a hardware terminal, but they do not
+have the same limitations.
+The chief limitation of a hardware terminal from the standpoint
+of your application is the management of dataflow, i.e., timing.
+Unless a hardware terminal is interfaced into a terminal concentrator
+(which does flow control),
+it (or your application) must manage dataflow, preventing overruns.
+The cheapest solution (no hardware cost)
+is for your program to do this by pausing after
+operations that the terminal does slowly, such as clearing the display.
+
+As a result, many terminal descriptions (including the vt100)
+have delay times embedded. You may wish to use these descriptions,
+but not want to pay the performance penalty.
+
+Set the NCURSES_NO_PADDING symbol to disable all but mandatory
+padding. Mandatory padding is used as a part of special control
+sequences such as \fIflash\fR.
+.TP 5
+NCURSES_NO_SETBUF
+Normally \fBncurses\fR enables buffered output during terminal initialization.
+This is done (as in SVr4 curses) for performance reasons.
+For testing purposes, both of \fBncurses\fR and certain applications,
+this feature is made optional. Setting the NCURSES_NO_SETBUF variable
+disables output buffering, leaving the output in the original (usually
+line buffered) mode.
+.TP 5
+NCURSES_TRACE
+During initialization, the \fBncurses\fR debugging library
+checks the NCURSES_TRACE symbol.
+If it is defined, to a numeric value, \fBncurses\fR calls the \fBtrace\fR
+function, using that value as the argument.
+
+The argument values, which are defined in \fBcurses.h\fR, provide several
+types of information.
+When running with traces enabled, your application will write the
+file \fBtrace\fR to the current directory.
+.TP 5
+TERM
+Denotes your terminal type.
+Each terminal type is distinct, though many are similar.
+.TP 5
+TERMCAP
+If the \fBncurses\fR library has been configured with \fItermcap\fR
+support, \fBncurses\fR will check for a terminal's description in
+termcap form if it is not available in the terminfo database.
+
+The TERMCAP symbol contains either a terminal description (with
+newlines stripped out),
+or a file name telling where the information denoted by the TERM symbol exists.
+In either case, setting it directs \fBncurses\fR to ignore
+the usual place for this information, e.g., /etc/termcap.
+.TP 5
+TERMINFO
+Overrides the directory in which \fBncurses\fR searches for your terminal
+description.
+This is the simplest, but not the only way to change the list of directories.
+The complete list of directories in order follows:
+.RS
+.TP 3
+-
+the last directory to which \fBncurses\fR wrote, if any, is searched first.
+.TP 3
+-
+the directory specified by the TERMINFO symbol
+.TP 3
+-
+$HOME/.terminfo
+.TP 3
+-
+directories listed in the TERMINFO_DIRS symbol
+.TP 3
+-
+one or more directories whose names are configured and compiled into the
+ncurses library, e.g.,
+@DATADIR@/terminfo
+.RE
+.TP 5
+TERMINFO_DIRS
+Specifies a list of directories to search for terminal descriptions.
+The list is separated by colons (i.e., ":").
+All of the terminal descriptions are in terminfo form, which makes
+a subdirectory named for the first letter of the terminal names therein.
+.TP 5
+TERMPATH
+If TERMCAP does not hold a file name then \fBncurses\fR checks
+the TERMPATH symbol.
+This is a list of filenames separated by colons (i.e., ":").
+If the TERMPATH symbol is not set, \fBncurses\fR looks in the files
+/etc/termcap, /usr/share/misc/termcap and $HOME/.termcap, in that order.
+.SH FILES
+.TP 5
+@DATADIR@/tabset
+directory containing initialization files for the terminal capability database
+@DATADIR@/terminfo
+terminal capability database