* doc/apt_preferences.5.xml:

  - explicitly warn against careless use (Closes: #567669)

debian/changelog

@@ -34,6 +34,8 @@ apt (0.7.26) UNRELEASED; urgency=low
     - include all existing Translation files in the Cache (Closes: 564137)
   * debian/control:
     - update with no changes to debian policy 3.8.4
+  * doc/apt_preferences.5.xml:
+    - explicitly warn against careless use (Closes: #567669)
 
   [ Ivan Masár ]
   * Slovak translation update. Closes: #568294

doc/apt_preferences.5.xml

@@ -14,7 +14,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>04 May 2009</date>
+   <date>16 February 2010</date>
  </refentryinfo>
 
  <refmeta>
@@ -53,6 +53,14 @@ earliest in the &sources-list; file.
 The APT preferences file does not affect the choice of instance, only
 the choice of version.</para>
 
+<para>Preferences are a strong power in the hands of a system administrator
+but they can become also their biggest nightmare if used without care!
+APT will not questioning the preferences so wrong settings will therefore
+lead to uninstallable packages or wrong decisions while upgrading packages.
+Even more problems will arise if multiply distribution releases are mixed
+without a good understanding of the following paragraphs.
+You have been warned.</para>
+
 <para>Note that the files in the <filename>/etc/apt/preferences.d</filename>
 directory are parsed in alphanumeric ascending order and need to obey the
 following naming convention: The files have no or "<literal>pref</literal>"