Mention "unquoted" identifiers are case-insensitive.

doc/src/sgml/syntax.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.139 2009/12/15 17:57:46 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.140 2010/02/03 22:48:55 momjian Exp $ -->
 
 <chapter id="sql-syntax">
  <title>SQL Syntax</title>
@@ -144,7 +144,7 @@ INSERT INTO MY_TABLE VALUES (3, 'hi there');
      <primary>case sensitivity</primary>
      <secondary>of SQL commands</secondary>
     </indexterm>
-    Identifier and key word names are case insensitive.  Therefore:
+    Unquoted identifier and key word names are case insensitive.  Therefore:
 <programlisting>
 UPDATE MY_TABLE SET A = 5;
 </programlisting>