diff --git a/usr.bin/rpcinfo/rpcinfo.8 b/usr.bin/rpcinfo/rpcinfo.8
--- a/usr.bin/rpcinfo/rpcinfo.8
+++ b/usr.bin/rpcinfo/rpcinfo.8
@@ -137,7 +137,7 @@
 .It Fl a Ar serv_address
 Use
 .Ar serv_address
-as the (universal) address for the service on
+as the universal address (uaddr) for the service on
 .Ar transport
 to ping procedure 0
 of the specified
@@ -149,6 +149,31 @@
 .Fl a
 option.
 .Pp
+The
+.Ar serv_address
+is specified in universal address format of the given transport.
+.Pp
+The format of a
+.Ar serv_address
+for IPv4 transports that use common 16-bit port numbers (TCP, SCTP, etc.)
+is expressed as a US-ASCII string:
+.Pp
+h1.h2.h3.h4.p1.p2
+.Pp
+.Bd
+including 'p1.p2' as a representation for a service port.
+For example, if a host has an address in hexadecimal of
+0xC0A8017D and there is a service listening on
+port 0x1621 (decimal 5665), then the complete uaddr is "192.168.1.125.22.33".
+.Ed
+Similarly, the format of the
+.Ar serv_address
+when used over IPv6 is the US-ASCII string:
+.Pp
+x1:x2:x3:x4:x5:x6:x7:x8.p1.p2
+.Pp
+and is computed identically to transports over IPv4.
+.Pp
 If
 .Ar versnum
 is not specified,
@@ -158,9 +183,7 @@
 This option avoids calls to remote
 .Nm rpcbind
 to find the address of the service.
-The
-.Ar serv_address
-is specified in universal address format of the given transport.
+.Pp
 .It Fl b
 Make an RPC broadcast to procedure 0
 of the specified
@@ -337,3 +360,9 @@
 .Xr netconfig 5 ,
 .Xr rpc 5 ,
 .Xr rpcbind 8
+.Rs
+.%A M. Eisler
+.%B IANA Considerations for Remote Procedure Call (RPC) Network Identifiers and Universal Address Formats
+.%C RFC 5665
+.%D Jan. 2010
+.Re