diff --git a/en_US.ISO8859-1/books/porters-handbook/book.sgml b/en_US.ISO8859-1/books/porters-handbook/book.sgml
index 6692632ab4..2f293f7088 100644
--- a/en_US.ISO8859-1/books/porters-handbook/book.sgml
+++ b/en_US.ISO8859-1/books/porters-handbook/book.sgml
@@ -9842,6 +9842,14 @@ bacula:*:910:</programlisting>
 	    <programlisting>ONLY_FOR_ARCHS= i386 amd64</programlisting>
 
 	    <programlisting>NOT_FOR_ARCHS= alpha ia64 sparc64</programlisting>
+
+	    <para>A custom <makevar>IGNORE</makevar> message can be set
+	      using <makevar>ONLY_FOR_ARCHS_REASON</makevar> and
+	      <makevar>NOT_FOR_ARCHS_REASON</makevar>.  Per architecture
+	      entries are possible with
+	      <makevar>ONLY_FOR_ARCHS_REASON_<replaceable>ARCH</replaceable></makevar>
+	      and
+	      <makevar>NOT_FOR_ARCHS_REASON_<replaceable>ARCH</replaceable></makevar>.
 	  </listitem>
 
 	</itemizedlist>