diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index b8996f64f0..4ca55bb927 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -11377,6 +11377,18 @@ zone <replaceable>zone_name</replaceable> <optional><replaceable>class</replacea
 	  <title><command>zone</command> Statement Definition and Usage</title>
 	  <sect3>
 	    <title>Zone Types</title>
+
+	    <para>
+	      The <command>type</command> keyword is required
+	      for the <command>zone</command> configuration unless
+	      it is an <command>in-view</command> configuration. Its
+	      acceptable values include: <varname>delegation-only</varname>,
+	      <varname>forward</varname>, <varname>hint</varname>,
+	      <varname>master</varname>, <varname>redirect</varname>,
+	      <varname>slave</varname>, <varname>static-stub</varname>,
+	      and <varname>stub</varname>.
+	    </para>
+
 	    <informaltable colsep="0" rowsep="0">
 	      <tgroup cols="2" colsep="0" rowsep="0" tgroupstyle="3Level-table">
 		<!--colspec colname="1" colnum="1" colsep="0" colwidth="1.108in"/-->