+The
+\fBgetyx\fR,
+\fBgetparyx\fR,
+\fBgetbegyx\fR and
+\fBgetmaxyx\fR
+macros are described in the XSI Curses standard, Issue 4.
+.PP
+This implementation also provides functions
+\fBgetbegx\fR,
+\fBgetbegy\fR,
+\fBgetcurx\fR,
+\fBgetcury\fR,
+\fBgetmaxx\fR,
+\fBgetmaxy\fR,
+\fBgetparx\fR and
+\fBgetpary\fR
+for compatibility with older versions of curses.
+.PP
+Although X/Open Curses does not address this,
+many implementations provide members of the WINDOW structure
+containing values corresponding to these macros.
+For best portability, do not rely on using the data in WINDOW,
+since some implementations make WINDOW opaque (do not allow
+direct use of its members).
+.PP
+Besides the problem of opaque structures,
+the data stored in like-named members may not have like-values in
+different implementations.
+For example, the WINDOW._maxx and WINDOW._maxy values in ncurses
+have (at least since release 1.8.1) differed by one from some
+other implementations.
+The difference is hidden by means of the macro \fBgetmaxyx\fP.