-All routines that return an integer return \fBERR\fR upon failure and OK (SVr4
-specifies only "an integer value other than \fBERR\fR") upon successful
-completion, unless otherwise noted in the preceding routine descriptions.
+All routines that return an integer return \fBERR\fR upon failure and \fBOK\fP
+(SVr4 specifies only "an integer value other than \fBERR\fR")
+upon successful completion,
+unless otherwise noted in the preceding routine descriptions.
+.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.