Reference manual: Improve the documentation for external funs

system/doc/reference_manual/code_loading.xml

@@ -112,8 +112,8 @@ loop() ->
       <c>code_switch</c> to it. The process then will make a fully
       qualified call to <c>m:loop()</c> and change to current code.
       Note that <c>m:loop/0</c> must be exported.</p>
-    <p>For code replacement of funs to work, the tuple syntax
-      <c>{Module,FunctionName}</c> must be used to represent the fun.</p>
+    <p>For code replacement of funs to work, the syntax
+      <c>fun Module:FunctionName/Arity</c> should be used.</p>
   </section>
 
   <section>

system/doc/reference_manual/expressions.xml

@@ -995,13 +995,16 @@ fun (Arg1,...,ArgN) -> Name(Arg1,...,ArgN) end</pre>
     <p>In <c>Module:Name/Arity</c>, <c>Module</c> and <c>Name</c> are atoms
       and <c>Arity</c> is an integer.
       A fun defined in this way will refer to the function <c>Name</c>
-      with arity <c>Arity</c> in the <em>latest</em> version of module <c>Module</c>.
+      with arity <c>Arity</c> in the <em>latest</em> version of module
+      <c>Module</c>. A fun defined in this way will not be dependent on
+      the code for module in which it is defined.
       </p>
     <p>When applied to a number N of arguments, a tuple
       <c>{Module,FunctionName}</c> is interpreted as a fun, referring
       to the function <c>FunctionName</c> with arity N in the module
       <c>Module</c>. The function must be exported.
-      <em>This usage is deprecated.</em> 
+      <em>This usage is deprecated.</em> Use <c>fun Module:Name/Arity</c>
+      instead.
       See <seealso marker="#calls">Function Calls</seealso> for an example.</p>
     <p>More examples can be found in <em>Programming Examples</em>.</p>
   </section>