+</PRE><H3><a name="h3-Command-line-Utilities">Command-line Utilities</a></H3><PRE>
+ The command-line utilities such as <STRONG><A HREF="tic.1m.html">tic(1)</A></STRONG> provide a verbose option
+ which extends the set of messages written using the <STRONG>curses_trace</STRONG>
+ function. Both of these (<STRONG>-v</STRONG> and <STRONG>curses_trace</STRONG>) use the same variable
+ (<STRONG>_nc_tracing</STRONG>), which determines the messages which are written.
+
+ Because the command-line utilities may call initialization functions
+ such as <STRONG>setupterm</STRONG>, <STRONG>tgetent</STRONG> or <STRONG>use_extended_names</STRONG>, some of their
+ debugging output may be directed to the <EM>trace</EM> file if the <EM>NCURSES</EM><STRONG>_</STRONG><EM>TRACE</EM>
+ environment variable is set:
+
+ <STRONG>o</STRONG> messages produced in the utility are written to the standard error.
+
+ <STRONG>o</STRONG> messages produced by the underlying library are written to <EM>trace</EM>.
+
+ If <EM>ncurses</EM> is built without tracing, none of the latter are produced,
+ and fewer diagnostics are provided by the command-line utilities.
+
+
+</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
+ Routines which return a value are designed to be used as parameters to
+ the <STRONG>_tracef</STRONG> routine.
+
+
+</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
+ These functions are not part of the XSI interface. Some other curses
+ implementations are known to have similar features, but they are not
+ compatible with <EM>ncurses</EM>:
+
+ <STRONG>o</STRONG> SVr4 provided <STRONG>traceon</STRONG> and <STRONG>traceoff</STRONG>, to control whether debugging
+ information was written to the "trace" file. While the functions
+ were always available, this feature was only enabled if <STRONG>DEBUG</STRONG> was
+ defined when building the library.
+
+ The SVr4 tracing feature is undocumented.
+
+ <STRONG>o</STRONG> PDCurses provides <STRONG>traceon</STRONG> and <STRONG>traceoff</STRONG>, which (like SVr4) are
+ always available, and enable tracing to the "trace" file only when
+ a debug-library is built.
+
+ PDCurses has a short description of these functions, with a note
+ that they are not present in X/Open Curses, <EM>ncurses</EM> or NetBSD. It
+ does not mention SVr4, but the functions' inclusion in a header
+ file section labeled "Quasi-standard" hints at the origin.
+
+ <STRONG>o</STRONG> NetBSD does not provide functions for enabling/disabling traces.
+ It uses environment variables <EM>CURSES</EM><STRONG>_</STRONG><EM>TRACE</EM><STRONG>_</STRONG><EM>MASK</EM> and
+ <EM>CURSES</EM><STRONG>_</STRONG><EM>TRACE</EM><STRONG>_</STRONG><EM>FILE</EM> to determine what is traced, and where the
+ results are written. This is available only when a debug-library
+ is built.
+
+ The NetBSD tracing feature is undocumented.
+
+ A few <EM>ncurses</EM> functions are not provided when symbol versioning is
+ used:
+
+ _nc_tracebits, _tracedump, _tracemouse
+
+ The original <STRONG>trace</STRONG> routine was deprecated because it often conflicted
+ with application names.