-All routines return the integer \fBERR\fR upon failure and \fBOK\fR on success
-(the SVr4 manuals specify only "an integer value other than \fBERR\fR") upon
-successful completion.
+All functions return the integer \fBERR\fR upon failure and \fBOK\fR 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.