- These functions are not part of the XSI interface. Some
- other curses implementations are known to have similar,
- undocumented features, but they are not compatible with
- ncurses.
+ 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.