+ X/Open Curses, Issue 4, describes these functions. It specifies no
+ error conditions for them.
+
+ <EM>ncurses</EM> defines <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> identically to support legacy
+ applications. However, the latter is obsolete.
+
+ <STRONG>o</STRONG> X/Open Curses, Issue 4, Version 2 (1996), marked <STRONG>vwscanw</STRONG> as
+ requiring <EM>varargs.h</EM> and "TO BE WITHDRAWN", and specified <STRONG>vw_scanw</STRONG>
+ using the <EM>stdarg.h</EM> interface.
+
+ <STRONG>o</STRONG> X/Open Curses, Issue 5, Draft 2 (December 2007) marked <STRONG>vwscanw</STRONG>
+ (along with <STRONG>vwscanw</STRONG> and the <EM>termcap</EM> interface) as withdrawn. After
+ incorporating review comments, this became X/Open Curses, Issue 7
+ (2009).
+
+ <STRONG>o</STRONG> <EM>ncurses</EM> provides <STRONG>vwscanw</STRONG>, but marks it as deprecated.
+
+ X/Open Curses Issues 4 and 7 both state that these functions return <STRONG>ERR</STRONG>
+ or <STRONG>OK</STRONG>. This is likely an erratum.
+
+ <STRONG>o</STRONG> Since the underlying <STRONG>scanf(3)</STRONG> returns the number of successful
+ conversions, and SVr4 <EM>curses</EM> was documented to use this feature,
+ this may have been an editorial solecism introduced by X/Open,
+ rather than an intentional change.
+
+ <STRONG>o</STRONG> This implementation retains compatibility with SVr4 <EM>curses.</EM> As of
+ 2018, NetBSD <EM>curses</EM> also returns the number of successful
+ conversions. Both <EM>ncurses</EM> and NetBSD <EM>curses</EM> call <STRONG>vsscanf(3)</STRONG> to
+ scan the string, which returns <STRONG>EOF</STRONG> on error.
+
+ <STRONG>o</STRONG> Portable applications should test only if the return value is <STRONG>ERR</STRONG>,
+ and not compare it to <STRONG>OK</STRONG>, since that value (zero) might be
+ misleading.
+
+ One portable way to get useful results would be to use a "%n"
+ conversion at the end of the format string, and check the value of
+ the corresponding variable to determine how many conversions
+ succeeded.