Index: en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml
===================================================================
--- en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml
+++ en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml
@@ -520,6 +520,19 @@
   <sect1 xml:id="dads-arch">
     <title>Architectural Considerations</title>
 
+    <para>Some ports are affected by features particular to one
+      or more of &os;'s supported architectures (as defined by
+      <literal>TARGETS</literal> in
+      <link xlink:href="https://svnweb.freebsd.org/base/head/Makefile">base/head/Makefile</link>).
+      This value is presented to ports <literal>Makefile</literal>s
+      as <literal>ARCH</literal>.</para>
+
+    <note>
+      <para>To see the complete list, run <command>make targets</command>.
+	The values to test <literal>ARCH</literal> against are the values
+	on the right-hand side of the <literal>/</literal>.</para>
+    </note>
+
     <sect2 xml:id="dads-arch-neutral">
       <title>Marking a Port as Architecture Neutral</title>
 
@@ -529,10 +542,26 @@
     </sect2>
 
     <sect2 xml:id="dads-arch-ignore">
-      <title>Marking a Port as Ignored Only On Certain Architectures</title>
+      <title>Marking a Port as Broken/Ignored On An Architecture</title>
 
+      <para>To mark a port as <literal>BROKEN</literal> or
+	<literal>IGNORE</literal> based on architecture:</para>
+
       <itemizedlist>
 	<listitem>
+	  <programlisting>IGNORE_i386=		does not run on i386</programlisting>
+
+	  <programlisting>BROKEN_powerpc64=	not ported to powerpc64 yet</programlisting>
+	</listitem>
+      </itemizedlist>
+
+    </sect2>
+
+    <sect2 xml:id="dads-arch-x_for">
+      <title>Marking a Port as Ignored Only On Multiple Architectures</title>
+
+      <itemizedlist>
+	<listitem>
 	  <para>To mark a port as <varname>IGNORE</varname>d
 	    only on certain architectures, there are two other
 	    convenience variables that will automatically set
@@ -540,10 +569,14 @@
 	    <varname>ONLY_FOR_ARCHS</varname> and
 	    <varname>NOT_FOR_ARCHS</varname>.  Examples:</para>
 
-	  <programlisting>ONLY_FOR_ARCHS=	i386 amd64</programlisting>
+	  <programlisting>ONLY_FOR_ARCHS=	amd64 i386</programlisting>
 
-	  <programlisting>NOT_FOR_ARCHS=	ia64 sparc64</programlisting>
+	  <programlisting>NOT_FOR_ARCHS=	powerpc64 sparc64</programlisting>
 
+	  <note>
+	    <para>Please sort the entries in alpha order.</para>
+	  </note>
+
 	  <para>A custom <varname>IGNORE</varname> message can be
 	    set using <varname>ONLY_FOR_ARCHS_REASON</varname> and
 	    <varname>NOT_FOR_ARCHS_REASON</varname>.  Per
@@ -556,7 +589,43 @@
 
     </sect2>
 
+    <sect2 xml:id="dads-wordsize">
+      <title>Wordsize Considerations</title>
+
+      <itemizedlist>
+	<listitem>
+	  <para>Some ports behave differently based on wordsize; in current
+	    practice, this is usually 64-bit vs. 32-bit.</para>
+
+	  <note>
+	    <para>Tip: it is easier to use the shorthand below rather
+	      than testing for each individual value of
+	      <literal>ARCH</literal> in a string such as:<programlisting>
+.if ${ARCH} == armv6 || ${ARCH} == armv7 || ${ARCH} == i386 || ${ARCH} == mips || ${ARCH} == powerpc || ${ARCH} == powerpcspe
+</programlisting>
+	      </para>
+	  </note>
+
+	  <para>Here is the recommended usage:</para>
+
+	  <programlisting># modify MAKE_ENV on 64-bit archs
+.if ${ARCH:*M64*}
+MAKE_ENV+= ...
+.endif</programlisting>
+
+	  <programlisting># modify CONFIGURE_ARGS on 32-bit archs
+.if ! ${ARCH:*M64*}
+CONFIGURE_ARGS+= ...
+.endif</programlisting>
+
+	</listitem>
+      </itemizedlist>
+
+    </sect2>
+
     <sect2 xml:id="dads-arch-i386">
+      <title>i386-Specific Considerations</title>
+
       <itemizedlist>
 	<listitem>
 	  <para>If a port fetches i386 binaries and installs them,