Document "" and "<broadcast>".
diff --git a/Doc/lib/libsocket.tex b/Doc/lib/libsocket.tex
index baf6373..3b6cee0 100644
--- a/Doc/lib/libsocket.tex
+++ b/Doc/lib/libsocket.tex
@@ -33,6 +33,10 @@
socket object is automatically selected based on the address family
specified when the socket object was created.
+For IP addresses, two special forms are accepted instead of a host
+address: the empty string represents \code{INADDR_ANY}, and the string
+\code{"<broadcast>"} represents \code{INADDR_BROADCAST}.
+
All errors raise exceptions. The normal exceptions for invalid
argument types and out-of-memory conditions can be raised; errors
related to socket or address semantics raise the error \code{socket.error}.