Merge branch 'bjorn/system-documentation'

* bjorn/system-documentation:
  Replace "lambda head" with "fun" in compiler warning
  Remove an historical note about fun representation before R6B
  Replace mention of a tuple fun with an external fun
  Update Interoperability Tutorial
  Update System Principles
  Update Erlang Reference Manual
  Update Getting Started
  Update Programming Examples
  Update OAM Principles
  Update Installation Guide
  Update Embedded Systems User's Guide
  Update Efficiency Guide
  Update Design Principles

1 files changed, 171 insertions, 196 deletions

diff --git a/system/doc/system_principles/create_target.xmlsrc b/system/doc/system_principles/create_target.xmlsrc
index a8ee2d1245..7c566229ac 100644
--- a/system/doc/system_principles/create_target.xmlsrc
+++ b/system/doc/system_principles/create_target.xmlsrc
@@ -31,55 +31,54 @@
     <rev>A</rev>
     <file>create_target.xml</file>
   </header>
+  <marker id="creating upgrading target system"></marker>
 
-  <section>
-    <title>Introduction</title>
-    <p>When creating a system using Erlang/OTP, the most simple way is
-      to install Erlang/OTP somewhere, install the application specific
+    <p>When creating a system using Erlang/OTP, the simplest way is
+      to install Erlang/OTP somewhere, install the application-specific
       code somewhere else, and then start the Erlang runtime system,
-      making sure the code path includes the application specific code.</p>
-    <p>Often it is not desirable to use an Erlang/OTP system as is. A
-      developer may create new Erlang/OTP compliant applications for a
+      making sure the code path includes the application-specific code.</p>
+    <p>It is often not desirable to use an Erlang/OTP system as is. A
+      developer can create new Erlang/OTP-compliant applications for a
       particular purpose, and several original Erlang/OTP applications
-      may be irrelevant for the purpose in question. Thus, there is a
+      can be irrelevant for the purpose in question. Thus, there is a
       need to be able to create a new system based on a given
-      Erlang/OTP system, where dispensable applications are removed,
-      and a set of new applications are included. Documentation and
+      Erlang/OTP system, where dispensable applications are removed
+      and new applications are included. Documentation and
       source code is irrelevant and is therefore not included in the
       new system.</p>
-    <p>This chapter is about creating such a system, which we call a
+    <p>This chapter is about creating such a system, which is called a
       <em>target system</em>.</p>
-    <p>In the following sections we consider creating target systems with
-      different requirements of functionality:</p>
+    <p>The following sections deal with target systems
+      with different requirements of functionality:</p>
     <list type="bulleted">
-      <item>a <em>basic target system</em> that can be started by
-       calling the ordinary <c>erl</c> script, </item>
-      <item>a <em>simple target system</em> where also code
-       replacement in run-time can be performed, and</item>
-      <item>an <em>embedded target system</em> where there is also
+      <item>A <em>basic target system</em> that can be started by
+       calling the ordinary <c>erl</c> script.</item>
+      <item>A <em>simple target system</em> where also code
+       replacement in runtime can be performed.</item>
+      <item>An <em>embedded target system</em> where there is also
        support for logging output from the system to file for later
        inspection, and where the system can be started automatically
-       at boot time. </item>
+       at boot time.</item>
     </list>
-    <p>We only consider the case when Erlang/OTP is running on a UNIX
-      system.</p>
-    <p>In the <c>sasl</c> application there is an example Erlang
-      module <c>target_system.erl</c> that contains functions for
-      creating and installing a target system.  This module is used in
-      the examples below, and the source code of the module is listed
-      at the end of this chapter.</p>
-  </section>
+    <p>Here is only considered the case when Erlang/OTP is running on a
+      UNIX system.</p>
+    <p>The <c>sasl</c> application includes the example Erlang
+      module <c>target_system.erl</c>, which contains functions for
+      creating and installing a target system. This module is used in
+      the following examples. The source code of the module is listed
+      in <seealso marker="#listing of target system">
+      Listing of target_system.erl</seealso></p>
 
   <section>
     <marker id="create"/>
     <title>Creating a Target System</title>
     <p>It is assumed that you have a working Erlang/OTP system structured
-      according to the OTP Design Principles.</p>
-    <p><em>Step 1.</em> First create a <c>.rel</c> file (see <seealso
-      marker="sasl:rel">rel(4)</seealso>) that specifies the <c>erts</c>
-      version and lists all applications that should be included in the
-      new basic target system. An example is the following
-      <c>mysystem.rel</c> file:</p>
+      according to the OTP design principles.</p>
+    <p><em>Step 1.</em> Create a <c>.rel</c> file (see the
+      <seealso marker="sasl:rel">rel(4)</seealso> manual page in
+      SASL), which specifies the ERTS version and lists
+      all applications that are to be included in the new basic target
+      system. An example is the following <c>mysystem.rel</c> file:</p>
     <code type="none">
 %% mysystem.rel
 {release,
@@ -91,23 +90,23 @@
   {pea, "1.0"}]}.</code>
     <p>The listed applications are not only original Erlang/OTP
       applications but possibly also new applications that you have
-      written yourself (here exemplified by the application
-      <c>pea</c>). </p>
-    <p><em>Step 2.</em> From the directory where the <c>mysystem.rel</c>
-      file reside, start the Erlang/OTP system:</p>
+      written (here exemplified by the application Pea (<c>pea</c>)).</p>
+    <p><em>Step 2.</em> Start Erlang/OTP from the directory where
+      the <c>mysystem.rel</c> file resides:</p>
     <pre>
 os> <input>erl -pa /home/user/target_system/myapps/pea-1.0/ebin</input></pre>
-    <p>where also the path to the <c>pea-1.0</c> ebin directory is
-      provided. </p>
-    <p><em>Step 3.</em> Now create the target system: </p>
+    <p>Here also the path to the <c>pea-1.0</c> ebin directory is
+      provided.</p>
+    <p><em>Step 3.</em> Create the target system:</p>
     <pre>
 1> <input>target_system:create("mysystem").</input></pre>
-    <p>The <c>target_system:create/1</c> function does the following:</p>
+    <p>The function <c>target_system:create/1</c> performs the
+      following:</p>
     <list type="ordered">
-      <item>Reads the <c>mysystem.rel</c> file, and creates a new file
-      <c>plain.rel</c> which is identical to former, except that it
-       only lists the <c>kernel</c> and <c>stdlib</c> applications. </item>
-      <item>From the <c>mysystem.rel</c> and <c>plain.rel</c> files
+      <item>Reads the file <c>mysystem.rel</c> and creates a new file
+      <c>plain.rel</c> that is identical to the former, except that it
+       only lists the Kernel and STDLIB applications.</item>
+      <item>From the files <c>mysystem.rel</c> and <c>plain.rel</c>
        creates the files <c>mysystem.script</c>,
       <c>mysystem.boot</c>, <c>plain.script</c>, and
       <c>plain.boot</c> through a call to
@@ -124,26 +123,26 @@ releases/mysystem.rel
 lib/kernel-2.16.4/
 lib/stdlib-1.19.4/
 lib/sasl-2.3.4/
-lib/pea-1.0/        </code>
+lib/pea-1.0/</code>
         <p>The file <c>releases/FIRST/start.boot</c> is a copy of our
           <c>mysystem.boot</c></p>
 	<p>The release resource file <c>mysystem.rel</c> is duplicated
           in the tar file. Originally, this file was only stored in
-          the <c>releases</c> directory in order to make it possible
+          the <c>releases</c> directory to make it possible
           for the <c>release_handler</c> to extract this file
           separately. After unpacking the tar
           file, <c>release_handler</c> would automatically copy the
           file to <c>releases/FIRST</c>. However, sometimes the tar
           file is unpacked without involving
-          the <c>release_handler</c> (e.g. when unpacking the first
-          target system) and therefore the file is now instead
+          the <c>release_handler</c> (for example, when unpacking the
+          first target system). The file is therefore now instead
           duplicated in the tar file so no manual copying is
-          necessary.</p>
+          needed.</p>
       </item>
-      <item>Creates the temporary directory <c>tmp</c> and extracts the tar file
-      <c>mysystem.tar.gz</c> into that directory. </item>
-      <item>Deletes the <c>erl</c> and <c>start</c> files from
-      <c>tmp/erts-5.10.4/bin</c>. These files will be created again from
+      <item>Creates the temporary directory <c>tmp</c> and extracts
+      the tar file <c>mysystem.tar.gz</c> into that directory.</item>
+      <item>Deletes the files <c>erl</c> and <c>start</c> from
+      <c>tmp/erts-5.10.4/bin</c>. These files are created again from
       source when installing the release.</item>
       <item>Creates the directory <c>tmp/bin</c>.</item>
       <item>Copies the previously created file <c>plain.boot</c> to
@@ -151,31 +150,31 @@ lib/pea-1.0/        </code>
       <item>Copies the files <c>epmd</c>, <c>run_erl</c>, and
       <c>to_erl</c> from the directory <c>tmp/erts-5.10.4/bin</c> to
        the directory <c>tmp/bin</c>.</item>
-      <item>Creates the directory <c>tmp/log</c>, which will be used
+      <item>Creates the directory <c>tmp/log</c>, which is used
        if the system is started as embedded with the <c>bin/start</c>
        script.</item>
       <item>Creates the file <c>tmp/releases/start_erl.data</c> with
        the contents "5.10.4 FIRST". This file is to be passed as data
-       file to the <c>start_erl</c> script.
-      </item>
+       file to the <c>start_erl</c> script.</item>
       <item>Recreates the file <c>mysystem.tar.gz</c> from the directories
-       in the directory <c>tmp</c>, and removes <c>tmp</c>.</item>
+       in the directory <c>tmp</c> and removes <c>tmp</c>.</item>
     </list>
   </section>
 
   <section>
     <title>Installing a Target System</title>
     <p><em>Step 4.</em> Install the created target system in a
-      suitable directory. </p>
+      suitable directory.</p>
     <pre>
 2> <input>target_system:install("mysystem", "/usr/local/erl-target").</input></pre>
-    <p>The function <c>target_system:install/2</c> does the following:
+    <p>The function <c>target_system:install/2</c> performs the following:
       </p>
     <list type="ordered">
       <item>Extracts the tar file <c>mysystem.tar.gz</c> into the target
        directory <c>/usr/local/erl-target</c>.</item>
-      <item>In the target directory reads the file <c>releases/start_erl.data</c>
-       in order to find the Erlang runtime system version ("5.10.4").</item>
+      <item>In the target directory reads the file
+      <c>releases/start_erl.data</c> to find the Erlang runtime system
+       version ("5.10.4").</item>
       <item>Substitutes <c>%FINAL_ROOTDIR%</c> and <c>%EMU%</c> for
       <c>/usr/local/erl-target</c> and <c>beam</c>, respectively, in
        the files <c>erl.src</c>, <c>start.src</c>, and
@@ -184,97 +183,102 @@ lib/pea-1.0/        </code>
       <c>start</c>, and <c>run_erl</c> in the target <c>bin</c>
        directory.</item>
       <item>Finally the target <c>releases/RELEASES</c> file is created
-       from data in the <c>releases/mysystem.rel</c> file.</item>
+       from data in the file <c>releases/mysystem.rel</c>.</item>
     </list>
   </section>
 
   <section>
     <marker id="start"/>
     <title>Starting a Target System</title>
-    <p>Now we have a target system that can be started in various ways.</p>
-    <p>We start it as a <em>basic target system</em> by invoking</p>
+    <p>Now we have a target system that can be started in various ways.
+      We start it as a <em>basic target system</em> by invoking:</p>
     <pre>
 os> <input>/usr/local/erl-target/bin/erl</input></pre>
-    <p>where only the <c>kernel</c> and <c>stdlib</c> applications are
-      started, i.e. the system is started as an ordinary development
-      system. There are only two files needed for all this to work:
-      <c>bin/erl</c> file (obtained from <c>erts-5.10.4/bin/erl.src</c>)
-      and the <c>bin/start.boot</c> file (a copy of <c>plain.boot</c>).</p>
+    <p>Here only the Kernel and STDLIB applications are
+      started, that is, the system is started as an ordinary development
+      system. Only two files are needed for all this to work:</p>
+      <list type="ordered">
+	<item><c>bin/erl</c> (obtained from
+	<c>erts-5.10.4/bin/erl.src</c>)</item>
+	<item><c>bin/start.boot</c> (a copy of
+	<c>plain.boot</c>)</item>
+      </list>
     <p>We can also start a distributed system (requires <c>bin/epmd</c>).</p>
     <p>To start all applications specified in the original
-      <c>mysystem.rel</c> file, use the <c>-boot</c> flag as follows:</p>
+      <c>mysystem.rel</c> file, use flag <c>-boot</c> as follows:</p>
     <pre>
 os> <input>/usr/local/erl-target/bin/erl -boot /usr/local/erl-target/releases/FIRST/start</input></pre>
-    <p>We start a <em>simple target system</em> as above. The only difference
-      is that also the file <c>releases/RELEASES</c> is present for
-      code replacement in run-time to work.</p>
-    <p>To start an <em>embedded target system</em> the shell script
-      <c>bin/start</c> is used. That shell script calls
+    <p>We start a <em>simple target system</em> as above. The only
+      difference is that also the file <c>releases/RELEASES</c> is
+      present for code replacement in runtime to work.</p>
+    <p>To start an <em>embedded target system</em>, the shell script
+      <c>bin/start</c> is used. The script calls
       <c>bin/run_erl</c>, which in turn calls <c>bin/start_erl</c>
       (roughly, <c>start_erl</c> is an embedded variant of
-      <c>erl</c>). </p>
+      <c>erl</c>).</p>
     <p>The shell script <c>start</c>, which is generated from
       erts-5.10.4/bin/start.src during installation, is only an
-      example. You should edit it to suite your needs. Typically it is
+      example. Edit it to suite your needs. Typically it is
       executed when the UNIX system boots.</p>
     <p><c>run_erl</c> is a wrapper that provides logging of output from
-      the run-time system to file. It also provides a simple mechanism
+      the runtime system to file. It also provides a simple mechanism
       for attaching to the Erlang shell (<c>to_erl</c>).</p>
-    <p><c>start_erl</c> requires the root directory
-      (<c>"/usr/local/erl-target"</c>), the releases directory
-      (<c>"/usr/local/erl-target/releases"</c>), and the location of
-      the <c>start_erl.data</c> file. It reads the run-time system
-      version (<c>"5.10.4"</c>) and release version (<c>"FIRST"</c>) from
-      the <c>start_erl.data</c> file, starts the run-time system of the
-      version found, and provides <c>-boot</c> flag specifying the boot
-      file of the release version found
-      (<c>"releases/FIRST/start.boot"</c>).</p>
-    <p><c>start_erl</c> also assumes that there is <c>sys.config</c> in
-      release version directory (<c>"releases/FIRST/sys.config"</c>). That
-      is the topic of the next section (see below).</p>
-    <p>The <c>start_erl</c> shell script should normally not be
+    <p><c>start_erl</c> requires:</p>
+     <list type="ordered">
+	<item>The root directory (<c>"/usr/local/erl-target"</c>)</item>
+	<item>The releases directory
+	(<c>"/usr/local/erl-target/releases"</c></item>
+	<item>The location of the file <c>start_erl.data</c></item>
+     </list>
+     <p>It performs the following:</p>
+     <list type="ordered">
+	<item>Reads the runtime system version (<c>"5.10.4"</c>) and
+	release version (<c>"FIRST"</c>) from the file
+	<c>start_erl.data</c>.</item>
+	<item>Starts the runtime system of the version found.</item>
+	<item>Provides the flag <c>-boot</c> specifying the boot
+	file of the release version found
+	(<c>"releases/FIRST/start.boot"</c>).</item>
+     </list>
+    <p><c>start_erl</c> also assumes that there is <c>sys.config</c>
+      in the release version directory (<c>"releases/FIRST/sys.config"</c>).
+      That is the topic of the next section.</p>
+    <p>The <c>start_erl</c> shell script is normally not to be
       altered by the user.</p>
   </section>
 
   <section>
     <title>System Configuration Parameters</title>
-    <p>As was pointed out above <c>start_erl</c> requires a
-      <c>sys.config</c> in the release version directory
-      (<c>"releases/FIRST/sys.config"</c>). If there is no such a
-      file, the system start will fail. Hence such a file has to
-      be added as well.</p>
-    <p></p>
-    <p>If you have system configuration data that are neither file
-      location dependent nor site dependent, it may be convenient to
-      create the <c>sys.config</c> early, so that it becomes a part of
+    <p>As was mentioned in the previous section, <c>start_erl</c>
+      requires a <c>sys.config</c> in the release version directory
+      (<c>"releases/FIRST/sys.config"</c>). If there is no such
+      file, the system start fails. Such a file must therefore
+      also be added.</p>
+    <p>If you have system configuration data that is neither
+      file-location-dependent nor site-dependent, it can be convenient
+      to create <c>sys.config</c> early, so it becomes part of
       the target system tar file created by
-      <c>target_system:create/1</c>. In fact, if you create, in the
-      current directory, not only the <c>mysystem.rel</c> file, but
-      also a <c>sys.config</c> file, that latter file will be tacitly
+      <c>target_system:create/1</c>. In fact, if you in the
+      current directory create not only the file <c>mysystem.rel</c>,
+      but also file <c>sys.config</c>, the latter file is tacitly
       put in the appropriate directory.</p>
   </section>
 
   <section>
-    <title>Differences from the Install Script</title>
-    <p>The above <c>install/2</c> procedure differs somewhat from that
+    <title>Differences From the Install Script</title>
+    <p>The previous <c>install/2</c> procedure differs somewhat from that
       of the ordinary <c>Install</c> shell script. In fact, <c>create/1</c>
       makes the release package as complete as possible, and leave to the
-      <c>install/2</c> procedure to finish by only considering location
-      dependent files.</p>
+      <c>install/2</c> procedure to finish by only considering
+      location-dependent files.</p>
   </section>
 
   <section>
     <title>Creating the Next Version</title>
-
-    <p>
-      In this example the <c>pea</c> application has been changed, and
-      so are <c>erts</c>, <c>kernel</c>, <c>stdlib</c> and
-      <c>sasl</c>.
-    </p>
-
-    <p>
-      <em>Step 1.</em> Create the <c>.rel</c> file:
-    </p>
+    <p>In this example the Pea application has been changed, and
+      so are the applications ERTS, Kernel, STDLIB
+      and SASL.</p>
+    <p><em>Step 1.</em> Create the file <c>.rel</c>:</p>
     <code type="none">
 %% mysystem2.rel
 {release,
@@ -284,65 +288,49 @@ os> <input>/usr/local/erl-target/bin/erl -boot /usr/local/erl-target/releases/FI
   {stdlib, "2.0"},
   {sasl, "2.4"},
   {pea, "2.0"}]}.</code>
-    <p>
-      <em>Step 2.</em> Create the application upgrade file (see
-      <seealso marker="sasl:appup">appup(4)</seealso>) for <c>pea</c>,
-      for example:
-    </p>
+    <p><em>Step 2.</em> Create the application upgrade file (see the
+      <seealso marker="sasl:appup">appup(4)</seealso> manual page in
+      SASL) for Pea, for example:</p>
     <code type="none">
 %% pea.appup
 {"2.0",
  [{"1.0",[{load_module,pea_lib}]}],
  [{"1.0",[{load_module,pea_lib}]}]}.</code>
-    <p>
-      <em>Step 3.</em> From the directory where the
-      <c>mysystem2.rel</c> file reside, start the Erlang/OTP system:
-    </p>
+    <p><em>Step 3.</em> From the directory where the file
+      <c>mysystem2.rel</c> resides, start the Erlang/OTP system,
+      giving the path to the new version of Pea:</p>
     <pre>
 os> <input>erl -pa /home/user/target_system/myapps/pea-2.0/ebin</input></pre>
-    <p>giving the path to the new version of <c>pea</c>. </p>
-
-    <p>
-      <em>Step 4.</em> Create the release upgrade file (see <seealso
-      marker="sasl:relup">relup(4)</seealso>):
-    </p>
+    <p><em>Step 4.</em> Create the release upgrade file (see the
+      <seealso marker="sasl:relup">relup(4)</seealso> manual page in
+      SASL):</p>
     <pre>
-1> <input>systools:make_relup("mysystem2",["mysystem"],["mysystem"],[{path,["/home/user/target_system/myapps/pea-1.0/ebin","/my/old/erlang/lib/*/ebin"]}]).</input></pre>
-    <p>
-      where <c>"mysystem"</c> is the base release and
-      <c>"mysystem2"</c> is the release to upgrade to.
-    </p>
-    <p>
-      Note that the <c>path</c> option is used for pointing out the
+1> <input>systools:make_relup("mysystem2",["mysystem"],["mysystem"],
+    [{path,["/home/user/target_system/myapps/pea-1.0/ebin",
+    "/my/old/erlang/lib/*/ebin"]}]).</input></pre>
+    <p>Here <c>"mysystem"</c> is the base release and
+      <c>"mysystem2"</c> is the release to upgrade to.</p>
+    <p>The <c>path</c> option is used for pointing out the
       old version of all applications. (The new versions are already
-      in the code path - assuming of course that the erlang node on
+      in the code path - assuming of course that the Erlang node on
       which this is executed is running the correct version of
-      Erlang/OTP.)
-    </p>
-    <p>
-      <em>Step 5.</em> Create the new release:
-    </p>
+      Erlang/OTP.)</p>
+    <p><em>Step 5.</em> Create the new release:</p>
     <pre>
 2> <input>target_system:create("mysystem2").</input></pre>
-    <p>
-      Given that the <c>relup</c> file generated in step 4 above is
-      now located in the current directory, it will automatically be
-      included in the release package.
-    </p>
+    <p>Given that the file <c>relup</c> generated in Step 4 is
+      now located in the current directory, it is automatically
+      included in the release package.</p>
   </section>
 
   <section>
     <title>Upgrading the Target System</title>
-    <p>
-      This part is done on the target node, and for this example we
+    <p>This part is done on the target node, and for this example we
       want the node to be running as an embedded system with the
-      <c>-heart</c> option, allowing automatic restart of the
-      node. See <seealso marker="#start">Starting a Target
-      System</seealso> above for more information.
-    </p>
-    <p>
-      We add <c>-heart</c> to <c>bin/start</c>:
-    </p>
+      <c>-heart</c> option, allowing automatic restart of the node.
+      For more information, see  <seealso marker="#start">
+      Starting a Target System</seealso>.</p>
+    <p>We add <c>-heart</c> to <c>bin/start</c>:</p>
     <code type="none">
 #!/bin/sh
 ROOTDIR=/usr/local/erl-target/
@@ -354,36 +342,27 @@ fi
 
 START_ERL_DATA=${1:-$RELDIR/start_erl.data}
 
-$ROOTDIR/bin/run_erl -daemon /tmp/ $ROOTDIR/log "exec $ROOTDIR/bin/start_erl $ROOTDIR $RELDIR $START_ERL_DATA -heart</code>
-    <p>
-      And we use the simplest possible <c>sys.config</c>, which we
-      store in <c>releases/FIRST</c>:
-    </p>
+$ROOTDIR/bin/run_erl -daemon /tmp/ $ROOTDIR/log "exec $ROOTDIR/bin/start_erl $ROOTDIR\
+$RELDIR $START_ERL_DATA -heart</code>
+    <p>We use the simplest possible <c>sys.config</c>, which we
+      store in <c>releases/FIRST</c>:</p>
     <code type="none">
 %% sys.config
 [].</code>
-    <p>
-      Finally, in order to prepare the upgrade, we need to put the new
+    <p>Finally, to prepare the upgrade, we must put the new
       release package in the <c>releases</c> directory of the first
-      target system:
-    </p>
+      target system:</p>
     <pre>
 os> <input>cp mysystem2.tar.gz /usr/local/erl-target/releases</input></pre>
-    <p>
-      And assuming that the node has been started like this:
-    </p>
+    <p>Assuming that the node has been started as follows:</p>
     <pre>
 os> <input>/usr/local/erl-target/bin/start</input></pre>
-    <p>
-      it can be accessed like this:
-    </p>
+    <p>It can be accessed as follows:</p>
     <pre>
 os> <input>/usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.1</input></pre>
-    <p>
-      Also note that logs can be found in
+    <p>Logs can be found in
       <c>/usr/local/erl-target/log</c>. This directory is specified as
-      an argument to <c>run_erl</c>in the start script listed above.
-    </p>
+      an argument to <c>run_erl</c>in the start script listed above.</p>
     <p>
       <em>Step 1.</em> Unpack the release:
     </p>
@@ -402,18 +381,19 @@ heart: Tue Apr  1 12:15:11 2014: Executed "/usr/local/erl-target/bin/start /usr/
       The above return value and output after the call to
       <c>release_handler:install_release/1</c> means that the
       <c>release_handler</c> has restarted the node by using
-      <c>heart</c>. This will always be done when the upgrade involves
-      a change of <c>erts</c>, <c>kernel</c>, <c>stdlib</c> or
-      <c>sasl</c>. See <seealso marker="upgrade">Upgrade when
-      Erlang/OTP has Changed</seealso> for more infomation about this.
+      <c>heart</c>. This is always done when the upgrade involves
+      a change of the applications ERTS, Kernel,
+      STDLIB, or SASL. For more information, see
+      <seealso marker="upgrade">
+      Upgrade when Erlang/OTP has Changed</seealso>.
     </p>
     <p>
-      The node will be accessible via a new pipe:
+      The node is accessible through a new pipe:
     </p>
     <pre>
 os> <input>/usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</input></pre>
     <p>
-      Let's see which releases we have in our system:
+      Check which releases there are in the system:
     </p>
     <pre>
 1> <input>release_handler:which_releases().</input>
@@ -426,7 +406,7 @@ os> <input>/usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</input></pre>
     <p>
       Our new release, "SECOND", is now the current release, but we
       can also see that our "FIRST" release is still permanent. This
-      means that if the node would be restarted at this point, it
+      means that if the node would be restarted now, it
       would come up running the "FIRST" release again.
     </p>
     <p>
@@ -434,11 +414,9 @@ os> <input>/usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</input></pre>
     </p>
     <pre>
 2> <input>release_handler:make_permanent("SECOND").</input></pre>
-
     <p>
-      Now look at the releases again:
+      Check the releases again:
     </p>
-
     <pre>
 3> <input>release_handler:which_releases().</input>
 <output>[{"MYSYSTEM","SECOND",
@@ -447,19 +425,16 @@ os> <input>/usr/local/erl-target/bin/to_erl /tmp/erlang.pipe.2</input></pre>
  {"MYSYSTEM","FIRST",
   ["kernel-2.16.4","stdlib-1.19.4","sasl-2.3.4","pea-1.0"],
   old}]</output></pre>
-
   <p>
-    Here we see that the new release version is <c>permanent</c>, so
-    it would be safe to restart the node.
-  </p>
-
+    We see that the new release version is <c>permanent</c>, so
+    it would be safe to restart the node.</p>
   </section>
 
   <section>
+    <marker id="listing of target system"/>
     <title>Listing of target_system.erl</title>
     <p>This module can also be found in the <c>examples</c> directory
-      of the <c>sasl</c> application.</p>
+      of the SASL application.</p>
     <codeinclude file="../../../lib/sasl/examples/src/target_system.erl" tag="%module" type="erl"></codeinclude>
-
   </section>
 </chapter>