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diff --git a/ghc/docs/users_guide/glasgow_exts.xml b/ghc/docs/users_guide/glasgow_exts.xml
index 7dca09a..c9dfaf0 100644
--- a/ghc/docs/users_guide/glasgow_exts.xml
+++ b/ghc/docs/users_guide/glasgow_exts.xml
@@ -1092,8 +1092,12 @@ because GHC does not allow  unboxed tuples on the left of a function arrow.
 
 <para>
 The idea of using existential quantification in data type declarations
-was suggested by Laufer (I believe, thought doubtless someone will
-correct me), and implemented in Hope+. It's been in Lennart
+was suggested by Perry, and implemented in Hope+ (Nigel Perry, <emphasis>The Implementation
+of Practical Functional Programming Languages</emphasis>, PhD Thesis, University of
+London, 1991). It was later formalised by Laufer and Odersky
+(<emphasis>Polymorphic type inference and abstract data types</emphasis>,
+TOPLAS, 16(5), pp1411-1430, 1994).
+It's been in Lennart
 Augustsson's <command>hbc</command> Haskell compiler for several years, and
 proved very useful.  Here's the idea.  Consider the declaration:
 </para>
@@ -4365,12 +4369,13 @@ can still define and use your own versions of
 </para>
 
 <para>
-To have the compiler ignore uses of assert, use the compiler option
-<option>-fignore-asserts</option>. <indexterm><primary>-fignore-asserts
-option</primary></indexterm> That is, expressions of the form
+GHC ignores assertions when optimisation is turned on with the
+      <option>-O</option><indexterm><primary><option>-O</option></primary></indexterm> flag.  That is, expressions of the form
 <literal>assert pred e</literal> will be rewritten to
-<literal>e</literal>.
-</para>
+<literal>e</literal>.  You can also disable assertions using the
+      <option>-fignore-asserts</option>
+      option<indexterm><primary><option>-fignore-asserts</option></primary>
+      </indexterm>.</para>
 
 <para>
 Assertion failures can be caught, see the documentation for the
@@ -4633,6 +4638,29 @@ key_function :: Int -> String -> (Bool, Double)
       </sect3>
     </sect2>
 
+    <sect2 id="language-pragma">
+      <title>LANGUAGE pragma</title>
+
+      <indexterm><primary>LANGUAGE</primary><secondary>pragma</secondary></indexterm>
+      <indexterm><primary>pragma</primary><secondary>LANGUAGE</secondary></indexterm>
+
+      <para>This allows language extensions to be enabled in a portable way.
+	It is the intention that all Haskell compilers support the
+	<literal>LANGUAGE</literal> pragma with the same syntax, although not
+	all extensions are supported by all compilers, of
+	course.  The <literal>LANGUAGE</literal> pragma should be used instead
+	of <literal>OPTIONS_GHC</literal>, if possible.</para>
+
+      <para>For example, to enable the FFI and preprocessing with CPP:</para>
+
+<programlisting>{-# LANGUAGE ForeignFunctionInterface, CPP #-}</programlisting>
+
+      <para>Any extension from the <literal>Extension</literal> type defined in
+	<ulink
+	  url="../libraries/Cabal/Language-Haskell-Extension.html"><literal>Language.Haskell.Extension</literal></ulink> may be used.  GHC will report an error if any of the requested extensions are not supported.</para>
+    </sect2>
+
+
     <sect2 id="line-pragma">
       <title>LINE pragma</title>
 
@@ -4643,9 +4671,7 @@ key_function :: Int -> String -> (Bool, Double)
       code.  It lets you specify the line number and filename of the
       original code; for example</para>
 
-<programlisting>
-{-# LINE 42 "Foo.vhs" #-}
-</programlisting>
+<programlisting>{-# LINE 42 "Foo.vhs" #-}</programlisting>
 
       <para>if you'd generated the current file from something called
       <filename>Foo.vhs</filename> and this line corresponds to line