diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 50d70b1cef..2d67885fd6 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.190 2007/02/01 00:28:16 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.191 2007/03/14 17:38:05 tgl Exp $ -->
 
  <chapter id="datatype">
   <title id="datatype-title">Data Types</title>
@@ -2243,12 +2243,13 @@ January 8 04:05:06 1999 PST
         were not already a recognized zone name, it would be accepted and would
         be functionally equivalent to USA East Coast time.  When a
         daylight-savings zone name is present, it is assumed to be used
-        according to USA time zone rules, so this feature is of limited use
-        outside North America.  One should also be wary that this provision can
-        lead to silently accepting bogus input, since there is no check on the
-        reasonableness of the zone abbreviations.  For example, <literal>SET
-        TIMEZONE TO FOOBAR0</> will work, leaving the system effectively using
-        a rather peculiar abbreviation for GMT.
+        according to the same daylight-savings transition rules used in the
+        <literal>zic</> time zone database's <filename>posixrules</> entry.
+        In a standard <productname>PostgreSQL</productname> installation,
+        <filename>posixrules</> is the same as <literal>US/Eastern</>, so
+        that POSIX-style time zone specifications follow USA daylight-savings
+        rules.  If needed, you can adjust this behavior by replacing the
+        <filename>posixrules</> file.
        </para>
       </listitem>
      </itemizedlist>
@@ -2259,6 +2260,14 @@ January 8 04:05:06 1999 PST
      rule and so have two possible UTC offsets.
     </para>
 
+    <para>
+     One should be wary that the POSIX-style time zone feature can
+     lead to silently accepting bogus input, since there is no check on the
+     reasonableness of the zone abbreviations.  For example, <literal>SET
+     TIMEZONE TO FOOBAR0</> will work, leaving the system effectively using
+     a rather peculiar abbreviation for UTC.
+    </para>
+
     <para>
      In all cases, timezone names are recognized case-insensitively.
      (This is a change from <productname>PostgreSQL</productname> versions
diff --git a/src/timezone/Makefile b/src/timezone/Makefile
index 3af8c376f8..f3d5088b4d 100644
--- a/src/timezone/Makefile
+++ b/src/timezone/Makefile
@@ -4,7 +4,7 @@
 #    Makefile for the timezone library
 
 # IDENTIFICATION
-#    $PostgreSQL: pgsql/src/timezone/Makefile,v 1.25 2007/02/09 15:56:00 petere Exp $
+#    $PostgreSQL: pgsql/src/timezone/Makefile,v 1.26 2007/03/14 17:38:06 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -23,6 +23,10 @@ TZDATA = africa antarctica asia australasia europe northamerica southamerica \
 	pacificnew etcetera factory backward systemv solar87 solar88 solar89
 TZDATAFILES = $(TZDATA:%=$(srcdir)/data/%)
 
+# which zone should determine the DST rules (not the specific UTC offset!)
+# for POSIX-style timezone specs
+POSIXRULES = US/Eastern
+
 all: SUBSYS.o submake-libpgport zic
 
 SUBSYS.o: $(OBJS)
@@ -32,7 +36,7 @@ zic: $(ZICOBJS)
 	$(CC) $(CFLAGS) $(ZICOBJS) $(LDFLAGS) $(LIBS) -o $@$(X)
 
 install: all installdirs
-	./zic -d '$(DESTDIR)$(datadir)/timezone' $(TZDATAFILES)
+	./zic -d '$(DESTDIR)$(datadir)/timezone' -p '$(POSIXRULES)' $(TZDATAFILES)
 	$(MAKE) -C tznames $@
 
 installdirs: