Documented getprotobyname() interface.
diff --git a/Doc/lib/libsocket.tex b/Doc/lib/libsocket.tex
index b105b22..3743100 100644
--- a/Doc/lib/libsocket.tex
+++ b/Doc/lib/libsocket.tex
@@ -107,6 +107,15 @@
host (most likely containing only a single address).
\end{funcdesc}
+\begin{funcdesc}{getprotobyname}{protocolname}
+Translate an Internet protocol name (e.g. \code{'icmp'}) to a constant
+suitable for passing as the (optional) third argument to the
+\code{socket()} function. This is usually only needed for sockets
+opened in ``raw'' mode (\code{SOCK_RAW}); for the normal socket modes,
+the correct protocol is chosen automatically if the protocol is
+omitted or zero.
+\end{funcdesc}
+
\begin{funcdesc}{getservbyname}{servicename\, protocolname}
Translate an Internet service name and protocol name to a port number
for that service. The protocol name should be \code{'tcp'} or