diff --git a/en_US.ISO8859-1/books/porters-handbook/book.sgml b/en_US.ISO8859-1/books/porters-handbook/book.sgml
index 385c47857e..0ecb28697e 100644
--- a/en_US.ISO8859-1/books/porters-handbook/book.sgml
+++ b/en_US.ISO8859-1/books/porters-handbook/book.sgml
@@ -4169,22 +4169,15 @@ PORTVERSION=   1.0</programlisting>
     </sect1>
 
     <sect1 id="conflicts">
-      <title><makevar>CONFLICTS</makevar></title>
+      <title>Conflict handling</title>
 
-	<para>If your package cannot coexist with other packages
-	  (because of file conflicts, runtime incompatibility, etc.),
-	  list the other package names in the <makevar>CONFLICTS</makevar>
-	  variable. You can use shell globs like <literal>*</literal> and
-	  <literal>?</literal> here.  Packages names should be
-	  enumerated the same way they appear in
-	  <filename>/var/db/pkg</filename>.  Please make sure that
-	  <makevar>CONFLICTS</makevar> does not match this port's
-	  package itself, or else forcing its installation with
-	  <makevar>FORCE_PKG_REGISTER</makevar> will no longer work.
-       </para>
+      <para>There are tree different variables to register a conflict
+	between packages and ports: <makevar>CONFLICTS</makevar>,
+	<makevar>CONFLICTS_INSTALL</makevar> and
+	<makevar>CONFLICTS_BUILD</makevar>.</para>
 
       <note>
-	<para><makevar>CONFLICTS</makevar> automatically sets
+	<para>The conflict variables automatically set the variable
 	  <makevar>IGNORE</makevar>, which is more fully documented
 	  in <xref linkend="dads-noinstall">.</para>
       </note>
@@ -4193,6 +4186,53 @@ PORTVERSION=   1.0</programlisting>
 	retain the <makevar>CONFLICTS</makevar> entries in those other ports
 	for a few months to cater for users who only update once in a
 	while.</para>
+
+      <sect2>
+	<title><makevar>CONFLICTS_INSTALL</makevar></title>
+
+	<para>If your package cannot coexist with other packages
+	  (because of file conflicts, runtime incompatibilities, etc.),
+	  list the other package names in the
+	  <makevar>CONFLICTS_INSTALL</makevar> variable.  You can use shell
+	  globs like <literal>*</literal> and <literal>?</literal> here.
+	  Packages names should be enumerated the same way they appear in
+	  <filename>/var/db/pkg</filename>.  Please make sure that
+	  <makevar>CONFLICTS_INSTALL</makevar> does not match this port's
+	  package itself.  Otherwise enforcing its installation with
+	  <makevar>FORCE_PKG_REGISTER</makevar> will no longer work.
+	  The CONFLICTS_INSTALL check is done after the build stage and
+	  prior to the install stage.</para>
+      </sect2>
+
+      <sect2>
+	<title><makevar>CONFLICTS_BUILD</makevar></title>
+
+	<para>If your port cannot be built if a certain port is already
+	  installed, list the other port names in the
+	  <makevar>CONFLICTS_BUILD</makevar> variable.  You can use shell
+	  globs like <literal>*</literal> and <literal>?</literal> here.
+	  Packages names should be enumerated the same way they appear in
+	  <filename>/var/db/pkg</filename>.  The CONFLICTS_BUILD check is
+	  done prior to the build stage.  Build conflicts are not recorded
+	  in the resulting package.</para>
+      </sect2>
+
+      <sect2>
+	<title><makevar>CONFLICTS</makevar></title>
+
+	<para>If your port cannot be built if a certain port is already
+	  installed and the resulting package cannot coexist with the
+	  other package, list the other package name in the
+	  <makevar>CONFLICTS</makevar> variable.  You can use shell
+	  globs like <literal>*</literal> and <literal>?</literal> here.
+	  Packages names should be enumerated the same way they appear in
+	  <filename>/var/db/pkg</filename>.  Please make sure that
+	  <makevar>CONFLICTS_INSTALL</makevar> does not match this port's
+	  package itself.  Otherwise enforcing its installation with
+	  <makevar>FORCE_PKG_REGISTER</makevar> will no longer work.
+	  The CONFLICTS check is done prior to the build stage and prior to
+	  the install stage.</para>
+      </sect2>
     </sect1>
 
     <sect1 id="install">