+ 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 ncurses:
+
+ <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 al-
+ ways 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, ncurses 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 <STRONG>CURSES_TRACE_MASK</STRONG> and <STRONG>CURS-</STRONG>
+ <STRONG>ES_TRACE_FILE</STRONG> 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 ncurses 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.