+All functions return the integer \fBERR\fP upon failure and \fBOK\fP on success.
+.PP
+X/Open does not define any error conditions.
+This implementation returns an error
+.bP
+if the window pointer is null or
+.bP
+if the string pointer is null or
+.bP
+if the corresponding calls to \fBwaddch\fP return an error.
+.PP
+Functions with a \*(``mv\*('' prefix first perform a cursor movement using
+\fBwmove\fP, and return an error if the position is outside the window,
+or if the window pointer is null.
+If an error is returned by the \fBwmove\fP,
+no characters are added to the window.
+.PP
+If an error is returned by \fBwaddch\fP
+(e.g.,
+because the window is not large enough,
+or an illegal byte sequence was detected)
+only part of the string may be added.
+Aside from that,
+there is a special case in \fBwaddch\fP where an error may be
+returned after successfully writing a character to the lower-right corner
+of a window when \fBscrollok\fP is disabled.