+ Old versions of curses, e.g., BSD 4.4, would return a null pointer from
+ <STRONG>initscr</STRONG> when an error is detected, rather than exiting. It is safe but
+ redundant to check the return value of <STRONG>initscr</STRONG> in XSI Curses.
+
+ Calling <STRONG>endwin</STRONG> does not dispose of the memory allocated in <STRONG>initscr</STRONG> or
+ <STRONG>newterm</STRONG>. Deleting a <STRONG>SCREEN</STRONG> provides a way to do this:
+
+ <STRONG>o</STRONG> X/Open Curses does not say what happens to <STRONG>WINDOW</STRONG>s when <STRONG>delscreen</STRONG>
+ "frees storage associated with the <STRONG>SCREEN</STRONG>" nor does the SVr4 docu-
+ mentation help, adding that it should be called after <STRONG>endwin</STRONG> if a
+ <STRONG>SCREEN</STRONG> is no longer needed.
+
+ <STRONG>o</STRONG> However, <STRONG>WINDOW</STRONG>s are implicitly associated with a <STRONG>SCREEN</STRONG>. so that
+ it is reasonable to expect <STRONG>delscreen</STRONG> to deal with these.
+
+ <STRONG>o</STRONG> SVr4 curses deletes the standard <STRONG>WINDOW</STRONG> structures <STRONG>stdscr</STRONG> and
+ <STRONG>curscr</STRONG> as well as a work area <STRONG>newscr</STRONG>. SVr4 curses ignores other
+ windows.
+
+ <STRONG>o</STRONG> Since version 4.0 (1996), ncurses has maintained a list of all win-
+ dows for each screen, using that information to delete those win-
+ dows when <STRONG>delscreen</STRONG> is called.
+
+ <STRONG>o</STRONG> NetBSD copied this feature of ncurses in 2001. PDCurses follows
+ the SVr4 model, deleting only the standard <STRONG>WINDOW</STRONG> structures.
+
+
+</PRE><H3><a name="h3-High-level-versus-low-level">High-level versus low-level</a></H3><PRE>
+ Different implementations may disagree regarding the level of some
+ functions. For example, <STRONG>SCREEN</STRONG> (returned by <STRONG>newterm</STRONG>) and <STRONG>TERMINAL</STRONG> (re-
+ turned by <STRONG><A HREF="curs_terminfo.3x.html">setupterm(3x)</A></STRONG>) hold file descriptors for the output stream.
+ If an application switches screens using <STRONG>set_term</STRONG>, or switches termi-
+ nals using <STRONG><A HREF="curs_terminfo.3x.html">set_curterm(3x)</A></STRONG>, applications which use the output file de-
+ scriptor can have different behavior depending on which structure holds
+ the corresponding descriptor.
+
+ For example
+
+ <STRONG>o</STRONG> NetBSD's <STRONG><A HREF="curs_termattrs.3x.html">baudrate(3x)</A></STRONG> function uses the descriptor in <STRONG>TERMINAL</STRONG>.
+ <STRONG>ncurses</STRONG> and SVr4 use the descriptor in <STRONG>SCREEN</STRONG>.
+
+ <STRONG>o</STRONG> NetBSD and <STRONG>ncurses</STRONG> use the descriptor in <STRONG>TERMINAL</STRONG> for terminal I/O
+ modes, e.g., <STRONG><A HREF="curs_kernel.3x.html">def_shell_mode(3x)</A></STRONG>, <STRONG><A HREF="curs_kernel.3x.html">def_prog_mode(3x)</A></STRONG>. SVr4 curses
+ uses the descriptor in <STRONG>SCREEN</STRONG>.