Index: en_US.ISO8859-1/books/porters-handbook/makefiles/chapter.xml
===================================================================
--- en_US.ISO8859-1/books/porters-handbook/makefiles/chapter.xml
+++ en_US.ISO8859-1/books/porters-handbook/makefiles/chapter.xml
@@ -4496,6 +4496,110 @@
 	</example>
       </sect3>
 
+      <sect3 xml:id="options-vars">
+	<title><varname><replaceable>OPT</replaceable>_VARS</varname></title>
+
+	<para>Provides a generic way to set and append to variables.
+	  Check in this chapter that there is not already an existing
+	  helper available before using this.</para>
+
+	<para>When option <replaceable>OPT</replaceable> is selected,
+	  and <varname><replaceable>OPT</replaceable>_VARS</varname>
+	  is defined, for each
+	  <literal><replaceable>key</replaceable>=<replaceable>value</replaceable></literal>
+	  pair of
+	  <varname><replaceable>OPT</replaceable>_VARS</varname>,
+	  <literal><replaceable>KEY</replaceable></literal> is set to
+	  <literal><replaceable>value</replaceable></literal>.  For
+	  each
+	  <literal><replaceable>key</replaceable>+=<replaceable>value</replaceable></literal>
+	  pair of
+	  <varname><replaceable>OPT</replaceable>_VARS</varname>,
+	  <literal><replaceable>value</replaceable></literal> is
+	  appended to
+	  <literal><replaceable>KEY</replaceable></literal>.
+	  example:</para>
+
+	<programlisting>OPTIONS_DEFINE=	OPT1 OPT2 OPT3
+OPT1_VARS=	also_build+=opt1
+OPT2_VARS=	also_build+=opt2
+OPT3_VARS=	opt3_build=yes
+
+MAKE_ARGS=	ALSO_BUILD="${ALSO_BUILD}" OPT3_BUILD="${OPT3_BUILD}"</programlisting>
+
+	<para>is equivalent to:</para>
+
+	<programlisting>OPTIONS_DEFINE=	OPT1 OPT2
+
+.include &lt;bsd.port.options.mk&gt;
+
+.if ${PORT_OPTIONS:MOPT1}
+ALSO_BUILD+=	opt1
+.endif
+
+.if ${PORT_OPTIONS:MOPT2}
+ALSO_BUILD+=	opt2
+.endif
+
+.if ${PORT_OPTIONS:MOPT2}
+OPT3_BUILD=	yes
+.endif
+
+MAKE_ARGS=	ALSO_BUILD="${ALSO_BUILD}" OPT3_BUILD="${OPT3_BUILD}"</programlisting>
+      </sect3>
+
+      <sect3 xml:id="options-vars-off">
+	<title><varname><replaceable>OPT</replaceable>_VARS_OFF</varname></title>
+
+	<para>Provides a generic way to set and append to variables.
+	  Check in this chapter that there is not already an existing
+	  helper available before using this.</para>
+
+	<para>When option <replaceable>OPT</replaceable> is not selected,
+	  and <varname><replaceable>OPT</replaceable>_VARS_OFF</varname>
+	  is defined, for each
+	  <literal><replaceable>key</replaceable>=<replaceable>value</replaceable></literal>
+	  pair of
+	  <varname><replaceable>OPT</replaceable>_VARS_OFF</varname>,
+	  <literal><replaceable>KEY</replaceable></literal> is set to
+	  <literal><replaceable>value</replaceable></literal>.  For
+	  each
+	  <literal><replaceable>key</replaceable>+=<replaceable>value</replaceable></literal>
+	  pair of
+	  <varname><replaceable>OPT</replaceable>_VARS_OFF</varname>,
+	  <literal><replaceable>value</replaceable></literal> is
+	  appended to
+	  <literal><replaceable>KEY</replaceable></literal>.
+	  example:</para>
+
+	<programlisting>OPTIONS_DEFINE=	OPT1 OPT2 OPT3
+OPT1_VARS_OFF=	no_build+=opt1
+OPT2_VARS_OFF=	no_build+=opt2
+OPT3_VARS_OFF=	opt3_build=no
+
+MAKE_ARGS=	NO_BUILD="${NO_BUILD}" OPT3_BUILD="${OPT3_BUILD}"</programlisting>
+
+	<para>is equivalent to:</para>
+
+	<programlisting>OPTIONS_DEFINE=	OPT1 OPT2
+
+.include &lt;bsd.port.options.mk&gt;
+
+.if ! ${PORT_OPTIONS:MOPT1}
+NO_BUILD+=	opt1
+.endif
+
+.if ! ${PORT_OPTIONS:MOPT2}
+NO_BUILD+=	opt2
+.endif
+
+.if ! ${PORT_OPTIONS:MOPT2}
+OPT3_BUILD=	yes
+.endif
+
+MAKE_ARGS=	NO_BUILD="${NO_BUILD}" OPT3_BUILD="${OPT3_BUILD}"</programlisting>
+      </sect3>
+
       <sect3 xml:id="options-dependencies">
 	<title>Dependencies</title>