Document the general effect of the comma operator

Closes: #574939

diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml
index be6f12f6abdb0f3f4604cc95e19da5db2fb80861..79132e007088de0f7c1a5f37a2d951c16005c49a 100644 (file)
--- a/doc/apt_preferences.5.xml
+++ b/doc/apt_preferences.5.xml
@@ -254,6 +254,11 @@ Pin-Priority: 500
 </programlisting>
 </listitem>
 </itemizedlist>
+
+The effect of the comma operator is similar to an "and" in logic: All
+conditions must be satisfied for the pin to match. There is one exception:
+For any type of condition (such as two "a" conditions), only the last such
+condition is checked.
 </para>
 
 </refsect2>