Add index entry.

diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 5455a2f2a5057fd1e3516029f7c163787019067b..2878e175ff3c63c00db89d5957bf71f22def5082 100644 (file)
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -3,6 +3,11 @@
 <chapter id="protocol">
  <title>Frontend/Backend Protocol</title>
 
+ <indexterm zone="protocol">
+  <primary>protocol</primary>
+  <secondary>frontend-backend</secondary>
+ </indexterm>
+
  <para>
   <productname>PostgreSQL</productname> uses a message-based protocol
   for communication between frontends and backends (clients and servers).