.Nm ypprot_err
.Nd Interface to the YP subsystem
.Sh SYNOPSIS
-.Fd #include <sys/types.h>
+.Fd #include <rpc/rpc.h>
.Fd #include <rpcsvc/ypclnt.h>
.Fd #include <rpcsvc/yp_prot.h>
.Ft int
.El
.It Fn yp_order
Returns the order number for a map.
+The order number is updated whenever a map is updated.
+Clients may use the order number to check whether they are using the most
+recent map.
.It Fn yp_master
Returns the hostname for the machine on which the master YP server process for
a map is running.