Index: TODO
===================================================================
diff -u -r2f7d2e507326a689d70c580f4cf8c4c82c420bac -r21e04cc3b201da5acfc77f7b05308f1ddfa606dc
--- TODO	(.../TODO)	(revision 2f7d2e507326a689d70c580f4cf8c4c82c420bac)
+++ TODO	(.../TODO)	(revision 21e04cc3b201da5acfc77f7b05308f1ddfa606dc)
@@ -5502,10 +5502,23 @@
 - see no need, why we should "set nodashalnum for int types"
 - extended regression test
 
+nsf.c:
+- remove redundant null check for object and add assertion
+
 documentation:
 - add current args to migration guide
 - fix cut&paste error: replace "current currentclass" by "current calledclass"
 
+Migration guide and tutorial:
+- updated "/cls/ info superclasses" and "/cls/ info subclasses"
+- updated "/cls/ info mixins" and "/obj/ info object mixins"
+- updated "/cls/ info filters" and "/obj/ info object filters"
+- dropped "/cls/ info mixin guard" and "/obj/ info object mixin guard"
+  dropped "/cls/ info filter guard" and "/obj/ info object filter guard"
+  (use "-guard option insteads)
+- updated "/cls/ mixins ...", "/obj/ object mixins ...",
+  "/cls/ filteres ...", "/obj/ object filters ..."
+
 ========================================================================
 TODO:
 
Index: doc/next-migration.html
===================================================================
diff -u -r2f7d2e507326a689d70c580f4cf8c4c82c420bac -r21e04cc3b201da5acfc77f7b05308f1ddfa606dc
--- doc/next-migration.html	(.../next-migration.html)	(revision 2f7d2e507326a689d70c580f4cf8c4c82c420bac)
+++ doc/next-migration.html	(.../next-migration.html)	(revision 21e04cc3b201da5acfc77f7b05308f1ddfa606dc)
@@ -3622,16 +3622,19 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-comment'># Register per-class mixin and guard for
+<pre class='nx'><span class='nx-comment'># Register/clear per-class mixin and guard for
 </span><span class='nx-comment'># a class
 </span>
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>mixin</span> add|<span class='nx-keyword'>set</span>|clear ...
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>mixin</span> <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>mixin</span>/ <span class='nx-placeholder'>?condition?</span>
+<span class='nx-placeholder'>/cls/</span> mixins add|<span class='nx-keyword'>set</span>|clear ...
+<span class='nx-placeholder'>/cls/</span> mixins <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>mixin</span>/ <span class='nx-placeholder'>?condition?</span>
 <span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>configure</span> -mixin ...
 
-<span class='nx-comment'># Query per-class mixin
-</span><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>mixin</span> get
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>cget</span> -mixin</pre></div></div></div></td>
+<span class='nx-comment'># Query per-class mixins
+</span><span class='nx-placeholder'>/cls/</span> mixins get
+<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>cget</span> -mixins
+
+<span class='nx-comment'># Query per-class mixins (without guards)
+</span><span class='nx-placeholder'>/cls/</span> mixins classes</pre></div></div></div></td>
 </tr>
 <tr>
 <td align="left" valign="middle"><div><div class="listingblock">
@@ -3648,7 +3651,7 @@
 <pre class='nx'><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>mixin</span> ...
 <span class='nx-placeholder'>/obj/</span> mixinguard /<span class='nx-keyword'>mixin</span>/ <span class='nx-placeholder'>?condition?</span>
 
-<span class='nx-comment'># Query per-object mixin
+<span class='nx-comment'># Query per-object mixins
 </span><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>mixin</span></pre></div></div></div></td>
 <td align="left" valign="middle"><div><div class="listingblock">
 <div class="content"><style type='text/css'>
@@ -3661,16 +3664,19 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-comment'># Register per-object mixin and guard for
+<pre class='nx'><span class='nx-comment'># Register/clear per-object mixin and guard for
 </span><span class='nx-comment'># an object
 </span>
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> add|<span class='nx-keyword'>set</span>|clear ...
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>mixin</span>/ <span class='nx-placeholder'>?condition?</span>
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>configure</span> -object-mixin ...
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> mixins add|<span class='nx-keyword'>set</span>|clear ...
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> mixins <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>mixin</span>/ <span class='nx-placeholder'>?condition?</span>
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>configure</span> -object-mixins ...
 
 <span class='nx-comment'># Query per-object mixin
-</span><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> get
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>cget</span> -object-mixin</pre></div></div></div></td>
+</span><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> mixins get
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>cget</span> -object-mixin
+
+<span class='nx-comment'># Query per-object mixins (without guards)
+</span><span class='nx-placeholder'>/cls/</span> mixins classes</pre></div></div></div></td>
 </tr>
 </tbody>
 </table>
@@ -3722,16 +3728,19 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-comment'># Register per-class filter and guard for
+<pre class='nx'><span class='nx-comment'># Register/clear per-class filter and guard for
 </span><span class='nx-comment'># a class
 </span>
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>filter</span> add|<span class='nx-keyword'>set</span>|clear ...
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>filter</span> <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>filter</span>/ <span class='nx-placeholder'>?condition?</span>
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>configure</span> -filter ...
+<span class='nx-placeholder'>/cls/</span> filters add|<span class='nx-keyword'>set</span>|clear ...
+<span class='nx-placeholder'>/cls/</span> filters <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>filter</span>/ <span class='nx-placeholder'>?condition?</span>
+<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>configure</span> -filters ...
 
-<span class='nx-comment'># Query per-class filter
-</span><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>filter</span> get
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>cget</span> -filter</pre></div></div></div></td>
+<span class='nx-comment'># Query per-class filters
+</span><span class='nx-placeholder'>/cls/</span> filters get
+<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>cget</span> -filters
+
+<span class='nx-comment'># Query per-class filters (without guards)
+</span><span class='nx-placeholder'>/cls/</span> filters <span class='nx-keyword'>methods</span></pre></div></div></div></td>
 </tr>
 <tr>
 <td align="left" valign="middle"><div><div class="listingblock">
@@ -3758,16 +3767,19 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-comment'># Register per-object filter and guard for
+<pre class='nx'><span class='nx-comment'># Register(clear per-object filter and guard for
 </span><span class='nx-comment'># an object
 </span>
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>filter</span> add|<span class='nx-keyword'>set</span>|clear ...
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>filter</span> <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>filter</span>/ <span class='nx-placeholder'>?condition?</span>
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>configure</span> -object-filter ...
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> filters add|<span class='nx-keyword'>set</span>|clear ...
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>object</span> filters <span class='nx-keyword'>guard</span> /<span class='nx-keyword'>filter</span>/ <span class='nx-placeholder'>?condition?</span>
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>configure</span> -object-filters ...
 
-<span class='nx-comment'># Query per-object filter
-</span><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>filter</span> get
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>cget</span> -object-filter</pre></div></div></div></td>
+<span class='nx-comment'># Query per-object filters
+</span><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>object</span> filters get
+<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>cget</span> -object-filters
+
+<span class='nx-comment'># Query per-object filters (without guards)
+</span><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>object</span> filters <span class='nx-keyword'>methods</span></pre></div></div></div></td>
 </tr>
 </tbody>
 </table>
@@ -3789,7 +3801,82 @@
 syntax</code>. In addition, NX provides means to query the type of
 a method, and NX allows to filter by the type of the method.</p></div>
 <div class="sect3">
-<h4 id="_list_methods_defined_by_classes">2.6.1. List methods defined by classes</h4>
+<h4 id="_list_sub_and_superclass_relations">2.6.1. List sub- and superclass relations</h4>
+<div class="paragraph"><p>While XOTcl used singular words for introspecting sub- and superclass
+relations, NX uses plural word to indicate that potentially a list of
+values is returned.</p></div>
+<div class="tableblock">
+<table rules="all"
+width="100%"
+frame="void"
+cellspacing="0" cellpadding="4">
+<col width="50%" />
+<col width="50%" />
+<thead>
+<tr>
+<th align="left" valign="middle">XOTcl </th>
+<th align="left" valign="middle">Next Scripting Language</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td align="left" valign="middle"><div><div class="listingblock">
+<div class="content"><style type='text/css'>
+.nx             {color: #000000; font-weight: normal; font-style: normal; padding-left: 10px}
+table.nx        {border-collapse: collapse; border-spacing: 3px;}
+.nx-linenr      {border-right: 1px solid #DDDDDD;padding-right: 5px; color: #2B547D;font-style: italic;}
+.nx-string      {color: #779977; font-weight: normal; font-style: italic;}
+.nx-comment     {color: #717ab3; font-weight: normal; font-style: italic;}
+.nx-keyword     {color: #7f0055; font-weight: normal; font-style: normal;}
+.nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
+.nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
+</style>
+<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>superclass</span> <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
+<td align="left" valign="middle"><div><div class="listingblock">
+<div class="content"><style type='text/css'>
+.nx             {color: #000000; font-weight: normal; font-style: normal; padding-left: 10px}
+table.nx        {border-collapse: collapse; border-spacing: 3px;}
+.nx-linenr      {border-right: 1px solid #DDDDDD;padding-right: 5px; color: #2B547D;font-style: italic;}
+.nx-string      {color: #779977; font-weight: normal; font-style: italic;}
+.nx-comment     {color: #717ab3; font-weight: normal; font-style: italic;}
+.nx-keyword     {color: #7f0055; font-weight: normal; font-style: normal;}
+.nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
+.nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
+</style>
+<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> superclasses <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
+</tr>
+<tr>
+<td align="left" valign="middle"><div><div class="listingblock">
+<div class="content"><style type='text/css'>
+.nx             {color: #000000; font-weight: normal; font-style: normal; padding-left: 10px}
+table.nx        {border-collapse: collapse; border-spacing: 3px;}
+.nx-linenr      {border-right: 1px solid #DDDDDD;padding-right: 5px; color: #2B547D;font-style: italic;}
+.nx-string      {color: #779977; font-weight: normal; font-style: italic;}
+.nx-comment     {color: #717ab3; font-weight: normal; font-style: italic;}
+.nx-keyword     {color: #7f0055; font-weight: normal; font-style: normal;}
+.nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
+.nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
+</style>
+<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> subclass <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
+<td align="left" valign="middle"><div><div class="listingblock">
+<div class="content"><style type='text/css'>
+.nx             {color: #000000; font-weight: normal; font-style: normal; padding-left: 10px}
+table.nx        {border-collapse: collapse; border-spacing: 3px;}
+.nx-linenr      {border-right: 1px solid #DDDDDD;padding-right: 5px; color: #2B547D;font-style: italic;}
+.nx-string      {color: #779977; font-weight: normal; font-style: italic;}
+.nx-comment     {color: #717ab3; font-weight: normal; font-style: italic;}
+.nx-keyword     {color: #7f0055; font-weight: normal; font-style: normal;}
+.nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
+.nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
+</style>
+<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> subclasses -type setter <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
+</tr>
+</tbody>
+</table>
+</div>
+</div>
+<div class="sect3">
+<h4 id="_list_methods_defined_by_classes">2.6.2. List methods defined by classes</h4>
 <div class="paragraph"><p>While XOTcl uses different names for obtaining different kinds of
 methods defined by a class, NX uses <code>info methods</code> in an orthogonal
 manner. NX allows as well to use the call protection to filter the
@@ -3920,7 +4007,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_methods_defined_by_objects">2.6.2. List methods defined by objects</h4>
+<h4 id="_list_methods_defined_by_objects">2.6.3. List methods defined by objects</h4>
 <div class="paragraph"><p>While XOTcl uses different names for obtaining different kinds of
 methods defined by an object, NX uses <code>info methods</code> in an orthogonal
 manner. NX allows as well to use the call protection to filter the
@@ -4051,7 +4138,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_check_existence_of_a_method">2.6.3. Check existence of a method</h4>
+<h4 id="_check_existence_of_a_method">2.6.4. Check existence of a method</h4>
 <div class="paragraph"><p>NX provides multiple ways of checking, whether a method exists; one
 can use <code>info method exists</code> to check, if a given method exists
 (return boolean), or one can use <code>info methods ?pattern?</code>, where
@@ -4109,7 +4196,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_callable_methods">2.6.4. List callable methods</h4>
+<h4 id="_list_callable_methods">2.6.5. List callable methods</h4>
 <div class="paragraph"><p>In order to obtain for an object the set of artefacts defined in the
  class hierarchy, NX uses <code>info lookup</code>. One can either lookup methods
  (via <code>info lookup methods</code>) or slots (via <code>info lookup slots</code>). The
@@ -4289,7 +4376,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_object_class_where_a_specified_method_is_defined">2.6.5. List object/class where a specified method is defined</h4>
+<h4 id="_list_object_class_where_a_specified_method_is_defined">2.6.6. List object/class where a specified method is defined</h4>
 <div class="paragraph"><p><code>info lookup</code> can be used as well to determine, where exactly an
  artefact is located. One can obtain this way a method handle, where
 a method or filter is defined.</p></div>
@@ -4369,7 +4456,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_definition_of_scripted_methods">2.6.6. List definition of scripted methods</h4>
+<h4 id="_list_definition_of_scripted_methods">2.6.7. List definition of scripted methods</h4>
 <div class="paragraph"><p>XOTcl contains a long list of <code>info</code> subcommands for different kinds of
 methods and for obtaining more detailed information about these
 methods.</p></div>
@@ -4644,7 +4731,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="info_configure_parameter">2.6.7. List Configure Parameters</h4>
+<h4 id="info_configure_parameter">2.6.8. List Configure Parameters</h4>
 <div class="paragraph"><p>The way, how newly created objects can be configured is determined in NX
 via properties. The configuration happens during creation via the
 methods <code>create</code> or <code>new</code> or during runtime via <code>configure</code>. These
@@ -4724,7 +4811,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_variable_declarations_property_and_variable">2.6.8. List Variable Declarations (property and variable)</h4>
+<h4 id="_list_variable_declarations_property_and_variable">2.6.9. List Variable Declarations (property and variable)</h4>
 <div class="tableblock">
 <table rules="all"
 width="100%"
@@ -4791,7 +4878,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_slots">2.6.9. List Slots</h4>
+<h4 id="_list_slots">2.6.10. List Slots</h4>
 <div class="tableblock">
 <table rules="all"
 width="100%"
@@ -4861,11 +4948,10 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_filter_or_mixins">2.6.10. List Filter or Mixins</h4>
-<div class="paragraph"><p>In NX all introspection options for filters are grouped under <code>info
-filter</code> and all introspection options for mixins are under <code>info
-mixin</code>. Therefore, NX follows here the approach of using hierarchical
-subcommands rather than using a flat namespace.</p></div>
+<h4 id="_list_filter_or_mixins">2.6.11. List Filter or Mixins</h4>
+<div class="paragraph"><p>In NX all introspection options for filters are provided via
+<code>info filters</code> and all introspection options for mixins are
+provided via <code>info mixins</code>.</p></div>
 <div class="tableblock">
 <table rules="all"
 width="100%"
@@ -4905,9 +4991,8 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>filter</span> <span class='nx-keyword'>methods</span> \
-   <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span>
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>filter</span> <span class='nx-keyword'>guard</span> <span class='nx-placeholder'>/name/</span></pre></div></div></div></td>
+<pre class='nx'><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>object</span> filters \
+   <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
 </tr>
 <tr>
 <td align="left" valign="middle"><div><div class="listingblock">
@@ -4935,9 +5020,8 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>filter</span> <span class='nx-keyword'>methods</span> \
-   <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span>
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>filter</span> <span class='nx-keyword'>guard</span> <span class='nx-placeholder'>/name/</span></pre></div></div></div></td>
+<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> filters \
+   <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
 </tr>
 <tr>
 <td align="left" valign="middle"><div><div class="listingblock">
@@ -4964,9 +5048,8 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> classes \
-   <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span>
-<span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> <span class='nx-keyword'>guard</span> <span class='nx-placeholder'>/name/</span></pre></div></div></div></td>
+<pre class='nx'><span class='nx-placeholder'>/obj/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>object</span> mixins \
+   <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
 </tr>
 <tr>
 <td align="left" valign="middle"><div><div class="listingblock">
@@ -4994,16 +5077,15 @@
 .nx-placeholder {color: #AF663F; font-weight: normal; font-style: italic;}
 .nx-variable    {color: #AF663F; font-weight: normal; font-style: normal;}
 </style>
-<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>mixin</span> classes \
-   <span class='nx-placeholder'>?-closure?</span> <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?pattern?</span>
-<span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>mixin</span> <span class='nx-keyword'>guard</span> <span class='nx-placeholder'>/name/</span></pre></div></div></div></td>
+<pre class='nx'><span class='nx-placeholder'>/cls/</span> <span class='nx-keyword'>info</span> mixins \
+   <span class='nx-placeholder'>?-closure?</span> <span class='nx-placeholder'>?-guards?</span> <span class='nx-placeholder'>?-heritage?</span> <span class='nx-placeholder'>?pattern?</span></pre></div></div></div></td>
 </tr>
 </tbody>
 </table>
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_definition_of_methods_defined_by_aliases_setters_or_forwarders">2.6.11. List definition of methods defined by aliases, setters or forwarders</h4>
+<h4 id="_list_definition_of_methods_defined_by_aliases_setters_or_forwarders">2.6.12. List definition of methods defined by aliases, setters or forwarders</h4>
 <div class="paragraph"><p>As mentioned earlier, <code>info method definition</code> can be used on every
 kind of method. The same call can be used to obtain the definition of
 a scripted method, a method-alias, a forwarder or a setter method.</p></div>
@@ -5053,7 +5135,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_method_handles">2.6.12. List Method-Handles</h4>
+<h4 id="_list_method_handles">2.6.13. List Method-Handles</h4>
 <div class="paragraph"><p>NX supports <em>method-handles</em> to provide means to obtain further
 information about a method or to change maybe some properties of a
 method. When a method is created, the method creating method returns
@@ -5124,7 +5206,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_type_of_a_method">2.6.13. List type of a method</h4>
+<h4 id="_list_type_of_a_method">2.6.14. List type of a method</h4>
 <div class="paragraph"><p>The method <code>info ?object? method type</code> is new in NX to obtain the type of the
 specified method.</p></div>
 <div class="tableblock">
@@ -5173,7 +5255,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_list_the_scope_of_mixin_classes">2.6.14. List the scope of mixin classes</h4>
+<h4 id="_list_the_scope_of_mixin_classes">2.6.15. List the scope of mixin classes</h4>
 <div class="paragraph"><p>NX provides a richer set of introspection options to obtain
 information, where mixins classes are mixed into.</p></div>
 <div class="tableblock">
@@ -5296,7 +5378,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_check_properties_of_object_and_classes">2.6.15. Check properties of object and classes</h4>
+<h4 id="_check_properties_of_object_and_classes">2.6.16. Check properties of object and classes</h4>
 <div class="paragraph"><p>Similar as noted before, NX uses rather a hierarchical approach of
 naming using multiple layers of subcommands).</p></div>
 <div class="tableblock">
@@ -5515,7 +5597,7 @@
 </div>
 </div>
 <div class="sect3">
-<h4 id="_call_stack_introspection">2.6.16. Call-stack Introspection</h4>
+<h4 id="_call_stack_introspection">2.6.17. Call-stack Introspection</h4>
 <div class="paragraph"><p>Call-stack introspection is very similar in NX and XOTcl. NX uses for
 subcommand the term <code>current</code> instead of <code>self</code>, since <code>self</code> has a
 strong connotation to the current object. The term <code>proc</code> is renamed
@@ -6304,7 +6386,7 @@
 alter all object/class relations (including
 class/superclass/object-mixin/&#8230;)
 <code>nsf::relation::set</code>. The class and superclass can be certainly queried
-in all variants with <code>info class</code> or <code>info superclass</code>.</p></div>
+in all variants with <code>info class</code> or <code>info superclasses</code>.</p></div>
 <div class="listingblock">
 <div class="content"><style type='text/css'>
 .nx             {color: #000000; font-weight: normal; font-style: normal; padding-left: 10px}
@@ -6335,7 +6417,7 @@
 <div class="sect3">
 <h4 id="_info_heritage">3.2.5. Info heritage</h4>
 <div class="paragraph"><p><code>info heritage</code> returns in XOTcl 1 the transitive superclass
-hierarchy, which is equivalent with <code>info superclass -closure</code> and
+hierarchy, which is equivalent with <code>info superclasses -closure</code> and
 therefore not necessary. In XOTcl 2 (and NX), <code>info heritage</code> includes
 as well the transitive per-class mixins.</p></div>
 </div>
@@ -6384,7 +6466,7 @@
 <div id="footer">
 <div id="footer-text">
 Version 2.0b5<br />
-Last updated 2014-09-11 20:14:03 CEST
+Last updated 2014-09-22 14:23:47 CEST
 </div>
 </div>
 </body>
Index: doc/next-migration.txt
===================================================================
diff -u -r2f7d2e507326a689d70c580f4cf8c4c82c420bac -r21e04cc3b201da5acfc77f7b05308f1ddfa606dc
--- doc/next-migration.txt	(.../next-migration.txt)	(revision 2f7d2e507326a689d70c580f4cf8c4c82c420bac)
+++ doc/next-migration.txt	(.../next-migration.txt)	(revision 21e04cc3b201da5acfc77f7b05308f1ddfa606dc)
@@ -92,7 +92,7 @@
   make these accesses explicit should encourage developer to implement
   well defined interfaces to provide access to instance variables.
 
-. *Additional Forms of Method Definition and Reuse:* 
+. *Additional Forms of Method Definition and Reuse:*
    The Next Scripting Language
    provides much more orthogonal means to _define, reuse and
    introspect_ scripted and C-implemented methods.
@@ -105,7 +105,7 @@
      to define explicitly public interfaces in order to use methods
      from other objects.
 
-   .. One can invoke in NX fully qualified methods to invoke 
+   .. One can invoke in NX fully qualified methods to invoke
      methods outside the precedence path.
 
    .. One can define in NX _hierachical method names_ (similar to
@@ -118,22 +118,22 @@
 
 . *Orthogonal Parameterization:*
    The Next Scripting Language provides an _orthogonal framework for
-   parametrization_ of methods and objects. 
+   parametrization_ of methods and objects.
    .. In NX, the same argument parser is used for
      * Scripted Methods
      * C-implemented methods and Tcl commands
      * Object Parametrization
-   ..  While XOTcl 1 provided only value-checkers for non-positional 
-     arguments for methods, the Next Scripting Framework provides 
+   ..  While XOTcl 1 provided only value-checkers for non-positional
+     arguments for methods, the Next Scripting Framework provides
      the same value checkers for positional and non-positional
-     arguments of methods, as well as for positional and 
+     arguments of methods, as well as for positional and
      non-positional configure parameters (`-parameter` in
-     XOTcl 1). 
+     XOTcl 1).
   .. While XOTcl 1 supported only non-positional arguments at the
     begin of the argument list, these can be used now at arbitrary
     positions.
 
-. *Value Checking:* 
+. *Value Checking:*
 
    .. The Next Scripting Language supports checking of the _input
      parmeters_ and the _return values_ of scripted and C-implemented
@@ -169,7 +169,7 @@
    * Significantly improved built-in profiling (results can be
      processed in Tcl).
 
-. *Significantly Improved Test Suite:* The regression test suite of 
+. *Significantly Improved Test Suite:* The regression test suite of
   Next Scripting Scripting framework contain now more than
   5.000 tests, and order of magnitude more than in XOTcl 1.6
 
@@ -194,7 +194,7 @@
 
 
 
-=== NX and XOTcl Scripts 
+=== NX and XOTcl Scripts
 
 Below is a small, introductory example showing an implementation of a
 class +Stack+ in NX and XOTcl. The purpose of this first example is
@@ -228,10 +228,10 @@
    :variable things ""
 
    :public method push {thing} {
-      set :things [linsert ${:things} 0 $thing] 
+      set :things [linsert ${:things} 0 $thing]
       return $thing
    }
-  
+
    :public method pop {} {
       set top [lindex ${:things} 0]
       set :things [lrange ${:things} 1 end]
@@ -250,14 +250,14 @@
 Stack instproc init {} {
    my instvar things
    set things ""
-} 
+}
 
 Stack instproc push {thing} {
    my instvar things
-   set things [linsert $things 0 $thing] 
+   set things [linsert $things 0 $thing]
    return $thing
 }
-  
+
 Stack instproc pop {} {
    my instvar things
    set top [lindex $things 0]
@@ -393,16 +393,16 @@
 
 The following examples show the definition of a class and its methods
 in the init-block of a class (NX only), and the definition of methods
-via separate top level calls (XOTcl and NX). 
+via separate top level calls (XOTcl and NX).
 
 [options="header",cols="asciidoc,asciidoc",frame="none",valign="middle"]
 |======================
 |XOTcl |Next Scripting Language
 
 |[source,tcl]
 ----------------
-# Define instance method 'foo' and object 
-# method 'bar' for a Class 'C' with separate 
+# Define instance method 'foo' and object
+# method 'bar' for a Class 'C' with separate
 # toplevel commands
 
 Class C
@@ -421,7 +421,7 @@
 ----------------
 [source,tcl]
 ----------------
-# Define instance method and object method 
+# Define instance method and object method
 # with separate commands
 
 Class create C
@@ -441,8 +441,8 @@
 
 |[source,tcl]
 ----------------
-# Define object method and set 
-# instance variable in the init-block of 
+# Define object method and set
+# instance variable in the init-block of
 # an object
 
 Object create o {
@@ -452,8 +452,8 @@
 ----------------
 [source,tcl]
 ----------------
-# Define object method and set 
-# instance variable with separate 
+# Define object method and set
+# instance variable with separate
 # commands
 
 Object create o
@@ -555,22 +555,22 @@
 ----------------
 # Define setter and getter methods in NX.
 #
-# NX does not provide own methods, but uses 
+# NX does not provide own methods, but uses
 # the low level framework commands, since
-# application developer will only seldomly 
+# application developer will only seldomly
 # need it.
 
 Class create C
 ::nsf::method::setter C p1
 ::nsf::method::setter C -per-object p2
 
-Object create o 
+Object create o
 ::nsf::method::setter o p3
 ----------------
 |======================
 
 NX supports in contrary to XOTcl the method +alias+ which can be used
-to register arbitrary Tcl commands or methods for an object or class 
+to register arbitrary Tcl commands or methods for an object or class
 under a provided method name. Aliases can be used to reuse a certain implementation in
 e.g. different object systems under potentially different names. In
 some respects aliases are similar to forwarders, but they do not
@@ -620,7 +620,7 @@
 # Method modifiers
 #
 #   "object",
-#   "public", 
+#   "public",
 #   "protected", and
 #   "private"
 #
@@ -634,7 +634,7 @@
 #   "public",
 #   "protected"
 #
-# are applicable for all kinds of 
+# are applicable for all kinds of
 # method defining methods:
 #
 #    method, forward, alias
@@ -666,15 +666,15 @@
 NX provides means for method hiding via the method modifier
 +private+. Hidden methods can be invoked only via the +-local+ flag,
 which means: "call the specified method defined in the same
-class/object as the currently executing method". 
+class/object as the currently executing method".
 
 [options="header",cols="asciidoc,asciidoc",frame="none",valign="middle"]
 |======================
 |XOTcl |Next Scripting Language
 
 |[source,tcl]
 ----------------
-# XOTcl provides no means for 
+# XOTcl provides no means for
 # method hiding
 ----------------
 |[source,tcl]
@@ -685,7 +685,7 @@
   :private method baz {a b} {expr {$a + $b}}	
   :public method foo {a b} {: -local baz $a $b}
 }
-    
+
 nx::Class create Sub -superclass Base {
   :public method bar {a b} {: -local baz $a $b}
   :private method baz {a b} {expr {$a * $b}}
@@ -711,14 +711,14 @@
 
 |[source,tcl]
 ----------------
-# XOTcl provides only method deletion with 
+# XOTcl provides only method deletion with
 # the equivalent of Tcl's "proc foo {} {}"
 /cls/ instproc foo {} {}
 /obj/ proc foo {} {}
 ----------------
 |[source,tcl]
 ----------------
-# Deletion of Methods 
+# Deletion of Methods
 #
 /cls/ delete method /name/
 /obj/ delete object method /name/
@@ -792,10 +792,10 @@
 variables:
 
 - Import instance variables via +instvar+ and access variables via +$varName+
-- Set or get instance variables via +my set varName ?value?+ or other 
+- Set or get instance variables via +my set varName ?value?+ or other
    variable accessing methods registered on +xotcl::Object+ such as
    +append+, +lappend+, +incr+, etc.
-- Register same-named accessor functions and set/get values 
+- Register same-named accessor functions and set/get values
    of instance variables via +my varName ?value?+
 
 In NX, the favored approach to access instance variables is to use
@@ -844,7 +844,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# Set own instance variable to a value via 
+# Set own instance variable to a value via
 # resolver (preferred and fastest way)
 
 ... method ... {
@@ -856,11 +856,11 @@
 ... instproc ... {
    my instvar /varName/
    set /varName/ ?value?
-} 
+}
 ----------------
 |[source,tcl]
 ----------------
-# Set own instance variable via 
+# Set own instance variable via
 # variable import
 
 ... method ... {
@@ -872,7 +872,7 @@
 ----------------
 ... instproc ... {
    set /varName/ [my set /otherVar/]
-} 
+}
 ----------------
 |[source,tcl]
 ----------------
@@ -886,7 +886,7 @@
 ----------------
 ... method ... {
    set /newVar/ ${:/otherVar/}
-} 
+}
 ----------------
 |[source,tcl]
 ----------------
@@ -922,8 +922,8 @@
 ----------------
 |[source,tcl]
 ----------------
-# Set instance variable of object obj to a 
-# value via resolver 
+# Set instance variable of object obj to a
+# value via resolver
 # (preferred way: define property on obj)
 
 /obj/ eval [list set :/varName/ ?value?]
@@ -934,7 +934,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# Read instance variable of object obj 
+# Read instance variable of object obj
 # via resolver
 
 set /varName/ [/obj/ eval {set :/otherVar/}]
@@ -948,7 +948,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# Read instance variable of object /obj/ 
+# Read instance variable of object /obj/
 # via import
 
 ... method ... {
@@ -962,10 +962,10 @@
 ----------------
 |[source,tcl]
 ----------------
-# Test existence of instance variable of 
+# Test existence of instance variable of
 # object obj
 
-/obj/ eval {info exists :/varName/} 
+/obj/ eval {info exists :/varName/}
 ----------------
 [source,tcl]
 ----------------
@@ -978,7 +978,7 @@
 While XOTcl 1 had very limited forms of parameters, XOTcl 2 and NX
 provide a generalized and highly orthogonal parameter machinery
 handling various kinds of value constraints (also called value
-checkers). Parameters are used to specify, 
+checkers). Parameters are used to specify,
 
 - how objects and classes are initialized (we call these parameter types
    _Configure Parameters_), and
@@ -1010,7 +1010,7 @@
 default values are used, etc.).  Such configuration parameters are
 supported in XOTcl primarily via the method +parameter+, which is used
 in XOTcl to define multiple parameters via a list of parameter
-specifications. 
+specifications.
 
 Since the term "parameter" is underspecified, NX uses a more
 differentiated terminology. NX distinguishes between configurable
@@ -1042,7 +1042,7 @@
 
 |[source,tcl]
 ----------------
-# Define class "Foo" with instance 
+# Define class "Foo" with instance
 # variables "x" and "y" initialized
 # on instance creation. The initialization
 # has to be performed in the constructor.
@@ -1057,17 +1057,17 @@
 # Create instance of the class Foo
 Foo f1
 
-# Object f1 has instance variables 
+# Object f1 has instance variables
 # x == 1 and y == 2
 ----------------
 |[source,tcl]
 ----------------
-# Define class "Foo" with instance variables 
+# Define class "Foo" with instance variables
 # "x" and "y" initialized on instance creation.
-# The method "variable" is similar in syntax 
-# to Tcl's "variable" command. During 
-# instance creation, the variable 
-# definitions are used for the 
+# The method "variable" is similar in syntax
+# to Tcl's "variable" command. During
+# instance creation, the variable
+# definitions are used for the
 # initialization of the variables of the object.
 
 Class create Foo {
@@ -1078,7 +1078,7 @@
 # Create instance of the class Foo
 Foo create f1
 
-# Object f1 has instance variables 
+# Object f1 has instance variables
 # x == 1 and y == 2
 ----------------
 |======================
@@ -1102,17 +1102,17 @@
 
 |[source,tcl]
 ----------------
-# No syntactic support for creating 
+# No syntactic support for creating
 # class variables
 ----------------
 |[source,tcl]
 ----------------
 
 # Define a object variable "V" with value 100 and
-# an instance variable "x". "V" is defined for the 
+# an instance variable "x". "V" is defined for the
 # class object Foo, "x" is defined in the
-# instances of the class. "object variable" works 
-# similar to "object method". 
+# instances of the class. "object variable" works
+# similar to "object method".
 
 Class create Foo {
   :object variable V 100
@@ -1143,7 +1143,7 @@
 
 |[source,tcl]
 ----------------
-# Parameters specified as a list 
+# Parameters specified as a list
 # (short form); parameter
 # "a" has no default, "b" has default "1"
 
@@ -1152,11 +1152,11 @@
 # Create instance of the class Foo
 Foo f1 -a 0
 
-# Object f1 has instance variables 
+# Object f1 has instance variables
 # a == 0 and b == 1
 
 # XOTcl registers automatically accessors
-# for the parameters. Use the accessor 
+# for the parameters. Use the accessor
 # "b" to output the value of variable "b"
 puts [f1 b]
 
@@ -1166,8 +1166,8 @@
 ----------------
 |[source,tcl]
 ----------------
-# Define property "a" and "b". The 
-# property "a" has no default, "b" has 
+# Define property "a" and "b". The
+# property "a" has no default, "b" has
 # default value "1"
 
 Class create Foo {
@@ -1178,10 +1178,10 @@
 # Create instance of the class Foo
 Foo create f1 -a 0
 
-# Object f1 has instance variables 
+# Object f1 has instance variables
 # a == 0 and b == 1
 
-# Use the method "cget" to query the value 
+# Use the method "cget" to query the value
 # of a configuration parameter
 puts [f1 cget -b]
 
@@ -1204,13 +1204,13 @@
 
 |[source,tcl]
 ----------------
-# "parameter" creates always accessor 
-# methods, accessor methods are 
+# "parameter" creates always accessor
+# methods, accessor methods are
 # always public, no "cget" is available.
 
 Class create Foo -parameter {a {b1}}
 
-# Use the accessor method to query 
+# Use the accessor method to query
 # the value of a configuration parameter
 puts [f1 b]
 
@@ -1219,21 +1219,21 @@
 f1 a 100
 
 # Use the accessor method to unset the
-# value of instance variable "a" n.a. via 
+# value of instance variable "a" n.a. via
 # accessor
 ----------------
 |[source,tcl]
 ----------------
-# Define property "a" and "b". The 
-# property "a" has no default, "b" has 
+# Define property "a" and "b". The
+# property "a" has no default, "b" has
 # default value "1"
 
 Class create Foo {
   :variable -accessor public a
   :property -accessor public {b 1}
 }
 
-# Use the accessor method to query 
+# Use the accessor method to query
 # the value of a configuration parameter
 puts [f1 b get]
 
@@ -1255,7 +1255,7 @@
 |XOTcl |Next Scripting Language
 |[source,tcl]
 ----------------
-# XOTcl provides no means to define 
+# XOTcl provides no means to define
 # configurable variables at the object
 # level
 ----------------
@@ -1293,25 +1293,25 @@
 
 |[source,tcl]
 ----------------
-# No value constraints for 
-# parameter available 
+# No value constraints for
+# parameter available
 ----------------
 |[source,tcl]
 ----------------
-# Predefined value constraints: 
-#    object, class, alnum, alpha, ascii, boolean, 
-#    control, digit, double, false, graph, integer, 
-#    lower, parameter, print, punct, space, true, 
+# Predefined value constraints:
+#    object, class, alnum, alpha, ascii, boolean,
+#    control, digit, double, false, graph, integer,
+#    lower, parameter, print, punct, space, true,
 #    upper, wordchar, xdigit
 #
 # User defined value constraints are possible.
-# All parameter value checkers can be turned on 
+# All parameter value checkers can be turned on
 # and off at runtime.
 #
 # Define a required boolean property "a"
 # and an integer property "b" with a default.
-# The first definition uses "properties", 
-# the second definition uses multiple 
+# The first definition uses "properties",
+# the second definition uses multiple
 # "property" statements.
 
 Class create Foo -properties {
@@ -1343,12 +1343,12 @@
 
 |[source,tcl]
 ----------------
-# Required parameter not available 
+# Required parameter not available
 ----------------
 |[source,tcl]
 ----------------
 # Required parameter:
-# Define a required property "a" and a 
+# Define a required property "a" and a
 # required boolean property "b"
 
 Class create Foo -properties {
@@ -1378,8 +1378,8 @@
 
 |[source,tcl]
 ---------------
-# Multiplicity for parameter 
-# not available 
+# Multiplicity for parameter
+# not available
 -----------------
 |[source,tcl]
 ----------------
@@ -1398,7 +1398,7 @@
 ----------------
 Class create Foo {
   :property {ints:integer,0..n ""}
-  :property objs:object,1..n 
+  :property objs:object,1..n
   :property obj:object,0..1
 }
 ----------------
@@ -1434,8 +1434,8 @@
    Attribute b -default 1
 }
 
-# Create instance of the class Foo 
-# and provide a value for instance 
+# Create instance of the class Foo
+# and provide a value for instance
 # variable "a"
 Foo f1 -a 0
 
@@ -1444,9 +1444,9 @@
 
 |[source,tcl]
 ----------------
-# Configurable parameters specified via the 
-# method "property" (supports method 
-# modifiers and scripted configuration; 
+# Configurable parameters specified via the
+# method "property" (supports method
+# modifiers and scripted configuration;
 # see below)
 
 Class create Foo {
@@ -1475,7 +1475,7 @@
 
 |[source,tcl]
 ----------------
-# Define parameter with an an 
+# Define parameter with an an
 # attribute-specific type checker
 
 Class Person -slots {
@@ -1494,7 +1494,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# Configure parameter with scripted 
+# Configure parameter with scripted
 # definition (init-block), defining a
 # property specific type checker
 
@@ -1517,7 +1517,7 @@
 
 The parameters provided by a class for the initialization of
 instances can be introspected via querying the parameters
-of the method create: +/cls/ info lookup parameters create+ 
+of the method create: +/cls/ info lookup parameters create+
 (see <<info_configure_parameter>>).
 
 ==== Delete Variable Handlers
@@ -1534,7 +1534,7 @@
 |[source,tcl]
 ----------------
 # Like deletion of Methods:
-# Delete on the object, where the 
+# Delete on the object, where the
 # variable handler is defined.
 
 /cls/ delete property /name/
@@ -1564,16 +1564,16 @@
 
 |[source,tcl]
 ----------------
-# Define method foo with non-positional 
-# parameters (x, y and y) and positional 
+# Define method foo with non-positional
+# parameters (x, y and y) and positional
 # parameter (a and b)
 
 Class C
 C instproc foo {
-   -x:integer 
-   -y:required 
-   -z 
-   a 
+   -x:integer
+   -y:required
+   -z
+   a
    b
 } {
    # ...
@@ -1585,17 +1585,17 @@
 ----------------
 |[source,tcl]
 ----------------
-# Define method foo with 
-# non-positional parameters 
-# (x, y and y) and positional 
+# Define method foo with
+# non-positional parameters
+# (x, y and y) and positional
 # parameter (a and b)
 
 Class create C {
    :public method foo {
-      -x:integer 
-      -y:required 
-      -z 
-      a 
+      -x:integer
+      -y:required
+      -z
+      a
       b
    } {
       # ...
@@ -1608,24 +1608,24 @@
 
 |[source,tcl]
 ----------------
-# Only leading non-positional 
-# parameters are available; no 
-# optional positional parameters, 
-# no value constraints on 
-# positional parameters, 
+# Only leading non-positional
+# parameters are available; no
+# optional positional parameters,
+# no value constraints on
+# positional parameters,
 # no multiplicity, ...
 ----------------
 |[source,tcl]
 ----------------
-# Define various forms of parameters 
+# Define various forms of parameters
 # not available in XOTcl 1
 
 Class create C {
-  # trailing (or interleaved) non-positional 
+  # trailing (or interleaved) non-positional
   # parameters
   :public method m1 {a b -x:integer -y} {
     # ...
-  } 
+  }
 
   # positional parameters with value constraints
   :public method m2 {a:integer b:boolean} {
@@ -1640,14 +1640,14 @@
   # parameter with multiplicity
   :public method m3 {-objs:object,1..n c:class,0..1} {
     # ...
-  } 
+  }
 
-  # In general, the same list of value 
-  # constraints as for configure parameter is 
+  # In general, the same list of value
+  # constraints as for configure parameter is
   # available (see above).
   #
-  # User defined value constraints are 
-  # possible. All parameter value checkers 
+  # User defined value constraints are
+  # possible. All parameter value checkers
   # can be turned on and off.
 }
 ----------------
@@ -1668,18 +1668,18 @@
 
 |[source,tcl]
 ----------------
-# No return value checking 
+# No return value checking
 # available
 ----------------
 |[source,tcl]
 ----------------
-# Define method foo with non-positional 
-# parameters (x, y and y) and positional 
+# Define method foo with non-positional
+# parameters (x, y and y) and positional
 # parameter (a and b)
 
 Class create C {
 
-  # Define method foo which returns an 
+  # Define method foo which returns an
   # integer value
   :method foo -returns integer {-x:integer} {
     # ...
@@ -1694,7 +1694,7 @@
   # integer value
   :forward ++ -returns integer ::expr 1 +
 
- # Define a method that has to return a 
+ # Define a method that has to return a
  # non-empty list of objects
  :public object method instances {} \
     -returns object,1..n {
@@ -1737,37 +1737,43 @@
 ----------------
 |[source,tcl]
 ----------------
-# Register per-class mixin and guard for 
+# Register/clear per-class mixin and guard for
 # a class
 
-/cls/ mixin add\|set\|clear ...
-/cls/ mixin guard /mixin/ ?condition?
+/cls/ mixins add\|set\|clear ...
+/cls/ mixins guard /mixin/ ?condition?
 /cls/ configure -mixin ...
 
-# Query per-class mixin
-/cls/ mixin get
-/cls/ cget -mixin
+# Query per-class mixins
+/cls/ mixins get
+/cls/ cget -mixins
+
+# Query per-class mixins (without guards)
+/cls/ mixins classes
 ----------------
 |[source,tcl]
 ----------------
 /obj/ mixin ...
 /obj/ mixinguard /mixin/ ?condition?
 
-# Query per-object mixin
+# Query per-object mixins
 /obj/ mixin
 ----------------
 |[source,tcl]
 ----------------
-# Register per-object mixin and guard for 
+# Register/clear per-object mixin and guard for
 # an object
 
-/obj/ object mixin add\|set\|clear ...
-/obj/ object mixin guard /mixin/ ?condition?
-/obj/ configure -object-mixin ...
+/obj/ object mixins add\|set\|clear ...
+/obj/ object mixins guard /mixin/ ?condition?
+/obj/ configure -object-mixins ...
 
 # Query per-object mixin
-/obj/ object mixin get
+/obj/ object mixins get
 /obj/ cget -object-mixin
+
+# Query per-object mixins (without guards)
+/cls/ mixins classes
 ----------------
 |======================
 
@@ -1778,26 +1784,29 @@
 
 |[source,tcl]
 ----------------
-# Register per-class filter and guard for 
+# Register per-class filter and guard for
 # a class
 /cls/ instfilter ...
 /cls/ instfilterguard /filter/ ?condition?
 
 # Query per-class filter
-/cls/ instfilter 
+/cls/ instfilter
 ----------------
 |[source,tcl]
 ----------------
-# Register per-class filter and guard for 
+# Register/clear per-class filter and guard for
 # a class
 
-/cls/ filter add\|set\|clear ...
-/cls/ filter guard /filter/ ?condition?
-/cls/ configure -filter ...
+/cls/ filters add\|set\|clear ...
+/cls/ filters guard /filter/ ?condition?
+/cls/ configure -filters ...
 
-# Query per-class filter
-/cls/ filter get 
-/cls/ cget -filter
+# Query per-class filters
+/cls/ filters get
+/cls/ cget -filters
+
+# Query per-class filters (without guards)
+/cls/ filters methods
 ----------------
 |[source,tcl]
 ----------------
@@ -1806,16 +1815,19 @@
 ----------------
 |[source,tcl]
 ----------------
-# Register per-object filter and guard for 
+# Register(clear per-object filter and guard for
 # an object
 
-/obj/ object filter add\|set\|clear ...
-/obj/ object filter guard /filter/ ?condition?
-/obj/ configure -object-filter ...
+/obj/ object filters add\|set\|clear ...
+/obj/ object filters guard /filter/ ?condition?
+/obj/ configure -object-filters ...
 
-# Query per-object filter
-/cls/ object filter get 
-/obj/ cget -object-filter
+# Query per-object filters
+/cls/ object filters get
+/obj/ cget -object-filters
+
+# Query per-object filters (without guards)
+/cls/ object filters methods
 ----------------
 |======================
 
@@ -1835,6 +1847,35 @@
 syntax+. In addition, NX provides means to query the type of
 a method, and NX allows to filter by the type of the method.
 
+==== List sub- and superclass relations
+
+While XOTcl used singular words for introspecting sub- and superclass
+relations, NX uses plural word to indicate that potentially a list of
+values is returned.
+
+[options="header",cols="asciidoc,asciidoc",frame="none",valign="middle"]
+|======================
+|XOTcl |Next Scripting Language
+
+|[source,tcl]
+----------------
+/cls/ info superclass ?pattern?
+----------------
+|[source,tcl]
+----------------
+/cls/ info superclasses ?pattern?
+----------------
+|[source,tcl]
+----------------
+/cls/ info subclass ?pattern?
+----------------
+|[source,tcl]
+----------------
+/cls/ info subclasses -type setter ?pattern?
+----------------
+|======================
+
+
 ==== List methods defined by classes
 
 While XOTcl uses different names for obtaining different kinds of
@@ -1979,7 +2020,7 @@
 |[source,tcl]
 ----------------
 /obj/ info lookup methods ... ?pattern?
-# Returns list of method names 
+# Returns list of method names
 ----------------
 |[source,tcl]
 ----------------
@@ -1989,14 +2030,14 @@
 ----------------
 # List only application specific methods
 /obj/ info lookup methods -source application ... ?pattern?
-# Returns list of method names 
+# Returns list of method names
 ----------------
 |[source,tcl]
 ----------------
 # Options for 'info methods'
 #
 # -incontext
-# -nomixins 
+# -nomixins
 ----------------
 |[source,tcl]
 ----------------
@@ -2006,7 +2047,7 @@
 # -callprotection ...
 # -incontext
 # -type ...
-# -nomixins 
+# -nomixins
 ----------------
 |[source,tcl]
 ----------------
@@ -2044,10 +2085,10 @@
 ==== List object/class where a specified method is defined
 
 +info lookup+ can be used as well to determine, where exactly an
- artefact is located. One can obtain this way a method handle, where 
-a method or filter is defined. 
+ artefact is located. One can obtain this way a method handle, where
+a method or filter is defined.
 
-The concept of a _method-handle_ is new in NX. The method-handle 
+The concept of a _method-handle_ is new in NX. The method-handle
 can be used to obtain more information about the method, such as
 e.g. the definition of the method.
 
@@ -2085,7 +2126,7 @@
 orthogonal. For example +info method definition+ can be used to obtain
 with a single command the full definition of a _scripted method_, and
 furthermore, it works as well the same way to obtain e.g. the
-definition of a _forwarder_ or an _alias_. 
+definition of a _forwarder_ or an _alias_.
 
 While XOTcl uses different names for info options for objects and
 classes (using the prefix "inst" for instance specific method), NX
@@ -2143,7 +2184,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# not needed, part of 
+# not needed, part of
 # "info ?object? method parameter"
 ----------------
 |[source,tcl]
@@ -2207,7 +2248,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# Return the parameters applicable to 
+# Return the parameters applicable to
 # the create method of a certain class.
 # class can be configured. A pattern can
 # be used to filter the results.
@@ -2218,20 +2259,20 @@
 
 /cls/ info lookup syntax create ?/pattern/?
 
-# "info lookup parameters configure" returns 
-# parameters available for configuring the 
-# current object  (might contain object 
+# "info lookup parameters configure" returns
+# parameters available for configuring the
+# current object  (might contain object
 # specific information)
 
 /obj/ info lookup parameters configure ?pattern?
 
-# "info lookup configure syntax" returns syntax of 
+# "info lookup configure syntax" returns syntax of
 # a call to configure in the Tcl parameter syntax
 
 /obj/ info lookup syntax configure
 
-# Obtain information from a parameter 
-# (as e.g. returned from "info lookup 
+# Obtain information from a parameter
+# (as e.g. returned from "info lookup
 # parameters configure").
 
 nsf::parameter::info name /parameter/
@@ -2249,14 +2290,14 @@
 
 |[source,tcl]
 ----------------
-# obtain parameter definitions defined 
+# obtain parameter definitions defined
 # for a class
 /cls/ info parameter
 ----------------
 |[source,tcl]
 ----------------
-# "info variables" returns handles of 
-# properties and variables defined by this 
+# "info variables" returns handles of
+# properties and variables defined by this
 # class or object
 
 /cls/ info variables ?pattern?
@@ -2269,7 +2310,7 @@
 
 /obj/ info lookup variables /pattern/
 
-# "info variable" lists details about a 
+# "info variable" lists details about a
 # single property or variable.
 
 /obj/ info variable definition /handle/
@@ -2311,7 +2352,7 @@
 /obj/ info lookup slots \
    ?-type ...? ?-source ... ?pattern?
 
-# Obtain definition, name or parameter from 
+# Obtain definition, name or parameter from
 # slot object
 
 /slotobj/ definition
@@ -2325,10 +2366,9 @@
 
 ==== List Filter or Mixins
 
-In NX all introspection options for filters are grouped under +info
-filter+ and all introspection options for mixins are under +info
-mixin+. Therefore, NX follows here the approach of using hierarchical
-subcommands rather than using a flat namespace.
+In NX all introspection options for filters are provided via
++info filters+ and all introspection options for mixins are
+provided via +info mixins+.
 
 [options="header",cols="asciidoc,asciidoc",frame="none",valign="middle"]
 |======================
@@ -2341,9 +2381,8 @@
 ----------------
 |[source,tcl]
 ----------------
-/obj/ info object filter methods \
+/obj/ info object filters \
    ?-guards? ?pattern?
-/obj/ info object filter guard /name/
 ----------------
 |[source,tcl]
 ----------------
@@ -2353,9 +2392,8 @@
 ----------------
 |[source,tcl]
 ----------------
-/cls/ info filter methods \
+/cls/ info filters \
    ?-guards? ?pattern?
-/cls/ info filter guard /name/
 ----------------
 |[source,tcl]
 ----------------
@@ -2364,9 +2402,8 @@
 ----------------
 |[source,tcl]
 ----------------
-/obj/ info object mixin classes \
+/obj/ info object mixins \
    ?-guards? ?pattern?
-/obj/ info object mixin guard /name/
 ----------------
 |[source,tcl]
 ----------------
@@ -2376,9 +2413,8 @@
 ----------------
 |[source,tcl]
 ----------------
-/cls/ info mixin classes \
-   ?-closure? ?-guards? ?pattern?
-/cls/ info mixin guard /name/
+/cls/ info mixins \
+   ?-closure? ?-guards? ?-heritage? ?pattern?
 ----------------
 |======================
 
@@ -2422,23 +2458,23 @@
 |[source,tcl]
 ----------------
 #
-# List the method handle of the specified method, 
-# can be used e.g. for aliases. "handle" is the short 
+# List the method handle of the specified method,
+# can be used e.g. for aliases. "handle" is the short
 # form of "definitionhandle".
 #
 /cls/ info method handle /methodName/
 /obj/ info object method handle /methodName/
 #
-# For ensemble methods (method name contains 
-# spaces) one can query as well the registration 
+# For ensemble methods (method name contains
+# spaces) one can query as well the registration
 # handle, which is the handle to the root of the
-# ensemble; the definiton handle points to the 
+# ensemble; the definiton handle points to the
 # leaf of the ensemble.
 #
 /cls/ info method registrationhandle /methodName/
 /obj/ info object method registrationhandle /methodName/
 #
-# For aliases, one can query the original 
+# For aliases, one can query the original
 # definition via "info method origin"
 #
 /cls/ info method origin /methodName/
@@ -2481,7 +2517,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# List objects, where /cls/ is a 
+# List objects, where /cls/ is a
 # per-object mixin
 
 /cls/ info mixinof -scope object ?-closure? \
@@ -2520,7 +2556,7 @@
 ==== Check properties of object and classes
 
 Similar as noted before, NX uses rather a hierarchical approach of
-naming using multiple layers of subcommands). 
+naming using multiple layers of subcommands).
 
 [options="header",cols="asciidoc,asciidoc",frame="none",valign="middle"]
 |======================
@@ -2553,7 +2589,7 @@
 cd # Check if object is an NX class
 /obj/ has type ::nx::Class
 
-# Check if object is a class in one of the 
+# Check if object is a class in one of the
 # NSF object systems
 ::nsf::is class /obj/
 ----------------
@@ -2566,7 +2602,7 @@
 # Check if class is an NX metaclass
 expr {[/cls/ info heritage ::nx::Class] ne ""}
 
-# Check if object is a metaclass in one of the 
+# Check if object is a metaclass in one of the
 # NSF object systems
 ::nsf::is metaclass /obj/
 ----------------
@@ -2586,7 +2622,7 @@
 |[source,tcl]
 ----------------
 # Return name of object (without namespace prefix)
-/obj/ info name 
+/obj/ info name
 ----------------
 |[source,tcl]
 ----------------
@@ -2700,7 +2736,7 @@
 ----------------
 |[source,tcl]
 ----------------
-# Returns method-handle of the 
+# Returns method-handle of the
 # method to be called via "next"
 current next
 ----------------
@@ -2865,7 +2901,7 @@
 ==== Parameter usage without a value
 
 In XOTcl 1, it was possible to call a parameter method during object
-creation via the dash-interface without a value (in the example below `-x`). 
+creation via the dash-interface without a value (in the example below `-x`).
 
 [source,tcl]
 ----------------
@@ -2897,9 +2933,9 @@
 
 NX does not define the methods +class+ and +superclass+ (like XOTcl), but allows to
 alter all object/class relations (including
-class/superclass/object-mixin/...)  
-+nsf::relation::set+. The class and superclass can be certainly queried 
-in all variants with +info class+ or +info superclass+.
+class/superclass/object-mixin/...)
++nsf::relation::set+. The class and superclass can be certainly queried
+in all variants with +info class+ or +info superclasses+.
 [source,tcl]
 ----------------
 # NX example
@@ -2920,8 +2956,9 @@
 reloading objects/classes in an running interpreter).
 
 ==== Info heritage
+
 +info heritage+ returns in XOTcl 1 the transitive superclass
-hierarchy, which is equivalent with +info superclass -closure+ and
+hierarchy, which is equivalent with +info superclasses -closure+ and
 therefore not necessary. In XOTcl 2 (and NX), +info heritage+ includes
 as well the transitive per-class mixins.
 
@@ -2930,19 +2967,19 @@
 All slot objects (also XOTcl slot objects) are now next-scripting
 objects of baseclass `::nx::Slot`. The name of the experimental
 default-setter `initcmd` was changed to `defaultcmd`. Code directly
-working on the slots objects has to be adapted. 
+working on the slots objects has to be adapted.
 
 === Obsolete Commands
 
 Parameter-classes were rarely used and have been replaced by the more
 general object parameterization. Therefore, `cl info parameterclass` has
-been removed. 
+been removed.
 
 === Stronger Checking
 
 The Next Scripting Framework performs stronger checking than XOTcl 1
 For example, the requiredness of slots in XOTcl 1 was just a
-comment, while XOTcl 2 enforces it. 
+comment, while XOTcl 2 enforces it.
 
 === Exit Handlers
 
Index: doc/next-tutorial/next-tutorial.html
===================================================================
diff -u -r2488a3699c78579fb1f4f1b4f2a8366946287fe5 -r21e04cc3b201da5acfc77f7b05308f1ddfa606dc
--- doc/next-tutorial/next-tutorial.html	(.../next-tutorial.html)	(revision 2488a3699c78579fb1f4f1b4f2a8366946287fe5)
+++ doc/next-tutorial/next-tutorial.html	(.../next-tutorial.html)	(revision 21e04cc3b201da5acfc77f7b05308f1ddfa606dc)
@@ -2779,11 +2779,11 @@
 </span><span class='nx-comment'># "d1" is created based on the definitions of the last example
 </span><span class='nx-comment'>#
 </span><span class='nx-comment'># Add the methods from "M1" as per-object mixin to "d1"
-</span>d1 <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> add M1
+</span>d1 <span class='nx-keyword'>object</span> mixins add M1
 
 <span class='nx-comment'>#
 </span><span class='nx-comment'># Add the methods from "M2" as per-class mixin to class "C"
-</span>C <span class='nx-keyword'>mixin</span> add M2
+</span>C mixins add M2
 
 <span class='nx-comment'># Invoke the method foo
 </span>d1 foo
@@ -3737,10 +3737,10 @@
 properties, also NX provides some predefined definitions. Since
 <code>Person</code> is a subclass of <code>nx::Object</code> also the configure parameters of
 <code>nx::Object</code> are inherited. In the introductory stack example, we used
-<code>-mixin</code> applied to an object to denote per-object mixins (see
-<a href="#xmp-using-class-safety">Listing 8</a>). Since <code>mixin</code>
+<code>-mixins</code> applied to an object to denote per-object mixins (see
+<a href="#xmp-using-class-safety">Listing 8</a>). Since <code>mixins</code>
 is defined as a parameter on <code>nx::Object</code> it can be used as an object
-parameter <code>-mixin</code> for all objects in NX. To put it in other words,
+parameter <code>-mixins</code> for all objects in NX. To put it in other words,
 every object can be configured to have per-object mixins. If we would
 remove this definition, this feature would be removed as well.</p></div>
 <div class="paragraph"><p>As shown in the introductory examples, every object can be configured
@@ -3782,16 +3782,16 @@
    Command:
       p1 <span class='nx-keyword'>info</span> <span class='nx-keyword'>lookup</span> syntax <span class='nx-keyword'>configure</span>
    Result:
-      -name <span class='nx-placeholder'>/value/</span> ?-birthday <span class='nx-placeholder'>/value/</span>? ?-object-mixin /mixinreg .../<span class='nx-placeholder'>?
-      ?</span>-class /<span class='nx-keyword'>class</span>/? ?-object-filter /filterreg .../? ?/__initblock/?
+      -name <span class='nx-placeholder'>/value/</span> ?-birthday <span class='nx-placeholder'>/value/</span>? ?-object-mixins /mixinreg .../<span class='nx-placeholder'>?
+      ?</span>-class /<span class='nx-keyword'>class</span>/? ?-object-filters /filterreg .../? ?/__initblock/?
 
 Configure parameter <span class='nx-keyword'>for</span> Student s1:
    Command:
       s1 <span class='nx-keyword'>info</span> <span class='nx-keyword'>lookup</span> syntax <span class='nx-keyword'>configure</span>
    Result:
       ?-oncampus <span class='nx-placeholder'>/boolean/</span>? -matnr <span class='nx-placeholder'>/value/</span> -name <span class='nx-placeholder'>/value/</span>
-      ?-birthday <span class='nx-placeholder'>/value/</span>? ?-object-mixin /mixinreg .../? ?-class /<span class='nx-keyword'>class</span>/<span class='nx-placeholder'>?
-      ?</span>-object-filter /filterreg .../? ?/__initblock/?</pre></td></tr></table></div></div>
+      ?-birthday <span class='nx-placeholder'>/value/</span>? ?-object-mixins /mixinreg .../? ?-class /<span class='nx-keyword'>class</span>/<span class='nx-placeholder'>?
+      ?</span>-object-filters /filterreg .../? ?/__initblock/?</pre></td></tr></table></div></div>
 <div class="paragraph"><p>The given paramter show, how (a) objects can be configured
 at runtime or (b) how new instances can be configured
 at creation time via the <code>new</code> or <code>create</code> methods.
@@ -3820,7 +3820,7 @@
 specified for a class, the default superclass is
 <code>nx::Object</code>. Therefore <code>nx::Object</code> is the default value for the
 parameter <code>superclass</code>.</p></div>
-<div class="paragraph"><p>Another frequently used parameter for classes is <code>-mixin</code> to denote
+<div class="paragraph"><p>Another frequently used parameter for classes is <code>-mixins</code> to denote
 per-class mixins (see e.g. the introductory Stack example in
 <a href="#xmp-class-safestack">Listing 10</a>), which is defined in
 the same way.</p></div>
@@ -3859,9 +3859,9 @@
    Command:
       <span class='nx-keyword'>nx::Class</span> <span class='nx-keyword'>info</span> <span class='nx-keyword'>lookup</span> syntax <span class='nx-keyword'>configure</span>
    Result:
-      ?-superclass /<span class='nx-keyword'>class</span> .../? ?-mixin /mixinreg .../<span class='nx-placeholder'>?
-      ?</span>-filter /filterreg .../? ?-object-mixin /mixinreg .../<span class='nx-placeholder'>?
-      ?</span>-class /<span class='nx-keyword'>class</span>/? ?-object-filter /filterreg .../? ?/__initblock/?</pre></td></tr></table></div></div>
+      ?-superclass /<span class='nx-keyword'>class</span> .../? ?-mixins /mixinreg .../<span class='nx-placeholder'>?
+      ?</span>-filters /filterreg .../? ?-object-mixins /mixinreg .../<span class='nx-placeholder'>?
+      ?</span>-class /<span class='nx-keyword'>class</span>/? ?-object-filters /filterreg .../? ?/__initblock/?</pre></td></tr></table></div></div>
 </div>
 <div class="sect3">
 <h4 id="_user_defined_parameter_types">4.3.3. User defined Parameter Types</h4>
@@ -4041,11 +4041,11 @@
 ::nx::Object <span class='nx-keyword'>create</span> o {
   <span class='nx-comment'># The class M is unknown at this point
 </span>
-  <span class='nx-keyword'>:object</span> <span class='nx-keyword'>mixin</span> add M
+  <span class='nx-keyword'>:object</span> mixins add M
   <span class='nx-comment'># The line above has triggered the unknown class handler,
 </span>  <span class='nx-comment'># class M is now defined
 </span>
-  <span class='nx-keyword'>puts</span> [<span class='nx-keyword'>:info</span> <span class='nx-keyword'>object</span> <span class='nx-keyword'>mixin</span> classes]
+  <span class='nx-keyword'>puts</span> [<span class='nx-keyword'>:info</span> <span class='nx-keyword'>object</span> mixins]
   <span class='nx-comment'># The output will be:
 </span>  <span class='nx-comment'>#     ***** __unknown called with &lt;::M&gt;
 </span>  <span class='nx-comment'>#     ::M
@@ -4156,7 +4156,7 @@
 <div id="footer">
 <div id="footer-text">
 Version 2.0b5<br />
-Last updated 2014-06-01 17:23:28 CEST
+Last updated 2014-09-22 14:25:50 CEST
 </div>
 </div>
 </body>
Index: doc/next-tutorial/next-tutorial.txt
===================================================================
diff -u -r2488a3699c78579fb1f4f1b4f2a8366946287fe5 -r21e04cc3b201da5acfc77f7b05308f1ddfa606dc
--- doc/next-tutorial/next-tutorial.txt	(.../next-tutorial.txt)	(revision 2488a3699c78579fb1f4f1b4f2a8366946287fe5)
+++ doc/next-tutorial/next-tutorial.txt	(.../next-tutorial.txt)	(revision 21e04cc3b201da5acfc77f7b05308f1ddfa606dc)
@@ -12,7 +12,7 @@
 
 .Abstract
 *****************************************************************************
-This document provides a tutorial for the Next Scripting 
+This document provides a tutorial for the Next Scripting
 Language NX.
 *****************************************************************************
 
@@ -119,14 +119,14 @@
    #
    # Stack of Things
    #
-   
+
    :variable things {}
 
    :public method push {thing} {
-      set :things [linsert ${:things} 0 $thing] 
+      set :things [linsert ${:things} 0 $thing]
       return $thing
    }
-  
+
    :public method pop {} {
       set top [lindex ${:things} 0]
       set :things [lrange ${:things} 1 end]
@@ -191,15 +191,15 @@
 --------------------------------------------------
 #!/usr/bin/env tclsh
 package require nx
- 
+
 nx::Class create Stack {
 
    #
    # Stack of Things
    #
    ....
 }
- 
+
 Stack create s1
 s1 push a
 s1 push b
@@ -272,10 +272,10 @@
    :object variable things {}
 
    :public object method push {thing} {
-      set :things [linsert ${:things} 0 $thing] 
+      set :things [linsert ${:things} 0 $thing]
       return $thing
    }
-  
+
    :public object method pop {} {
       set top [lindex ${:things} 0]
       set :things [lrange ${:things} 1 end]
@@ -295,7 +295,7 @@
    this single instance  (the object +stack+).
 
 - The definition for the methods +push+ and +pop+ are the same as
-  before, but here we defined these with +object method+. Therefore, 
+  before, but here we defined these with +object method+. Therefore,
   these two methods +push+ and +pop+ are object-specific.
 
 In order to use
@@ -352,12 +352,12 @@
   #
   # Implement stack safety by defining an additional
   # instance variable named "count" that keeps track of
-  # the number of stacked elements. The methods of 
+  # the number of stacked elements. The methods of
   # this class have the same names and argument lists
   # as the methods of Stack; these methods "shadow"
   # the methods of class Stack.
   #
-  
+
   :variable count 0
 
   :public method push {thing} {
@@ -428,8 +428,8 @@
 mixin class +Safety+ generates an error message (raises an exception),
 and does not invoke the method of the +Stack+.
 
-The last two commands in 
-<<xmp-using-class-safety,{xmp-using-class-safety}>> 
+The last two commands in
+<<xmp-using-class-safety,{xmp-using-class-safety}>>
 use introspection to query for the objects
 +s1+ and +s2+ in which order the involved classes are processed. This
 order is called the +precedence order+ and is obtained via +info
@@ -457,8 +457,8 @@
 [source,tcl,numbers]
 --------------------------------------------------
 #
-# Create a safe stack class by using Stack and mixin 
-# Safety 
+# Create a safe stack class by using Stack and mixin
+# Safety
 #
 nx::Class create SafeStack -superclass Stack -mixin Safety
 
@@ -468,7 +468,7 @@
 The difference of a per-class mixin and an per-object mixin is that
 the per-class mixin is applicable to all instances of the
 class. Therefore, we call these mixins also sometimes instance mixins.
-In our example in <<xmp-class-safestack,{xmp-class-safestack}>>, 
+In our example in <<xmp-class-safestack,{xmp-class-safestack}>>,
 +Safety+ is mixed into the definition of
 +SafeStack+. Therefore, all instances of the class +SafeStack+ (here
 the instance +s3+) will be using the safety definitions.
@@ -482,7 +482,7 @@
 Note that we could use +Safety+ as well as a per-class mixin on
 +Stack+. In this case, all stacks would be safe stacks and we could
 not provide a selective feature selection (which might be perfectly
-fine). 
+fine).
 
 === Define Different Kinds of Stacks
 
@@ -500,10 +500,10 @@
 --------------------------------------------------
 Stack create s4 {
 
-  # 
-  # Create a stack with a object-specific method 
-  # to check the type of entries 
   #
+  # Create a stack with a object-specific method
+  # to check the type of entries
+  #
 
   :public object method push {thing:integer} {
     next
@@ -534,7 +534,7 @@
 --------------------------------------------------
 nx::Class create IntegerStack -superclass Stack {
 
-  # 
+  #
   # Create a Stack accepting only integers
   #
 
@@ -555,7 +555,7 @@
 (applicable for their instances) and object-specific methods (methods
 defined on objects, which are only applicable for these objects). In
 this section, we introduce methods that are defined on the class
-objects. Such methods are sometimes called _class methods_ or 
+objects. Such methods are sometimes called _class methods_ or
 _static methods_.
 
 In NX classes are objects, they are specialized objects with
@@ -581,7 +581,7 @@
    :variable things {}
 
    :public method push {thing} {
-      set :things [linsert ${:things} 0 $thing] 
+      set :things [linsert ${:things} 0 $thing]
       return $thing
    }
 
@@ -629,7 +629,7 @@
    scoped variable. Such a variable is created during the invocation
    of the method, and it is deleted, when the method ends.  In the
    example below, the variable +a+ is method scoped.
-   
+
 - A variable with a single colon prefix refers to an instance
     variable.  An instance variable is part of the object; when the
     object is destroyed, its instance variables are deleted as well. In the
@@ -704,7 +704,7 @@
 [source,tcl,numbers]
 --------------------------------------------------
 #
-# Define a class Person with properties "name" 
+# Define a class Person with properties "name"
 # and "birthday"
 #
 nx::Class create Person {
@@ -713,7 +713,7 @@
 }
 
 #
-# Define a class Student as specialization of Person 
+# Define a class Student as specialization of Person
 # with additional properties
 #
 nx::Class create Student -superclass Person {
@@ -738,7 +738,7 @@
 during creation. The properties result in non-positional configure parameters
 which can be provided in any order. In our listing, we create an instance of
 +Person+ using the configure  parameter +name+ and provide the value of
-+Bob+ to the instance variable +name+.  
++Bob+ to the instance variable +name+.
 
 The class +Student+ is defined as a specialization of +Person+ with
 two additional properties: +matnr+ and +oncampus+. The property
@@ -762,7 +762,7 @@
 contains a default value. Providing a default value means that
 whenever we create an instance of this class the object will contain
 such an instance variable, even when we provide no value via the
-configure parameters. 
+configure parameters.
 
 In our listing, we create an instance of +Student+ using the two
 configure parameters +name+ and +matnr+. Finally, we use method +cget+
@@ -808,7 +808,7 @@
 Note that the variable definitions are inherited in the same way as
 properties. The example in <<xmp-variable, {xmp-variable}>> shows a
 class +Derived+ that inherits from +Base+. When an instance +d1+ is
-created, it will contain the two instance variables +x+ and +y+. 
+created, it will contain the two instance variables +x+ and +y+.
 Note that the variable declarations from +property+ and +variable+ are
 used to initialize (and to configure) the instances variables of an object.
 
@@ -857,10 +857,10 @@
 The basic building blocks of an object oriented program are object and
 classes, which contain named pieces of code, the methods.
 
-=========================================== 
-*Methods* are subroutines (pieces of code) associated with objects 
+===========================================
+*Methods* are subroutines (pieces of code) associated with objects
 and/or classes. A method has a name, receives optionally arguments
-during invocation and returns a value. 
+during invocation and returns a value.
 ===========================================
 
 Plain Tcl provides subroutines, which are not associated with objects
@@ -872,7 +872,7 @@
 detail later on. For the time being, we deal here with methods defined
 on classes, which are applicable for the instance of these classes.
 
-==== Scripted Methods 
+==== Scripted Methods
 
 Since NX is a scripting language, most methods are most likely
 scripted methods, in which the method body contains Tcl code.
@@ -922,8 +922,8 @@
 methods. Such methods are for example _accessors_, _forwarders_ and
 _aliases_.
 
-=========================================== 
-An *accessor method* is a method that accesses instance 
+===========================================
+An *accessor method* is a method that accesses instance
 variables of an object. A call to an accessor
 without arguments uses the accessor as a getter, obtaining the actual
 value of the associated variable. A call to an accessor with an
@@ -932,7 +932,7 @@
 ===========================================
 
 NX provides support for C-implemented accessor methods. Accessors have
-already been mentioned in the section about properties. When 
+already been mentioned in the section about properties. When
 the option +-accessor public|protected|private+ is provided to a
 +variable+ or +property+ definition, NX creates automatically a
 same-named accessors method.
@@ -956,12 +956,12 @@
 Dog create fido
 
 # Use the accessor "length" as a getter, to obtain the value
-# of a property. The following call returns the length of the 
+# of a property. The following call returns the length of the
 # tail of fido
 fido::tail length get
 
 # Use the accessor "length" as a setter, to alter the value
-# of a property. The following call changes the length of 
+# of a property. The following call changes the length of
 # the tail of fido
 fido::tail length set 10
 
@@ -976,7 +976,7 @@
 C-implemented accessor, that enforces the value constraint (here a
 floating point number, since length uses the value constraint
 +double+). Line 25 will therefore raise an exception, since the
-provided values cannot be converted to a double number. 
+provided values cannot be converted to a double number.
 
 [[xmp-fido3]]
 .Listing {counter:figure-number}: Forwarder Methods
@@ -985,7 +985,7 @@
 --------------------------------------------------
 nx::Class create Dog {
   :public method bark {} { puts "[self] Bark, bark, bark." }
-  :method init {} { 
+  :method init {} {
     Tail create [self]::tail
     :public object forward wag [self]::tail wag
   }
@@ -1009,7 +1009,7 @@
 redirects all calls of the form +fido wag+ with arbitrary arguments to
 the subobject +fido::tail+.
 
-=========================================== 
+===========================================
 A *forwarder method* is a
 C-implemented method that redirects an invocation for a certain method
 to either a method of another object or to some other method of the
@@ -1028,9 +1028,9 @@
 
 ==== Method-Aliases
 
-=========================================== 
-An *alias method* is a means to register either an existing method, 
-or a Tcl proc, or a Tcl command as a method with the provided 
+===========================================
+An *alias method* is a means to register either an existing method,
+or a Tcl proc, or a Tcl command as a method with the provided
 name on a class or object.
 ===========================================
 
@@ -1057,7 +1057,7 @@
 Dog create fido
 
 # The following line prints "::fido Bark, bark, bark."
-fido warn 
+fido warn
 --------------------------------------------------
 
 <<xmp-fido4,{xmp-fido4}>> extends the last example by defining an
@@ -1073,12 +1073,12 @@
 All kinds of methods might have different kind of protections in NX.
 The call-protection defines from which calling context methods might
 be called. The Next Scripting Framework supports as well redefinition
-protection for methods. 
+protection for methods.
 
 NX distinguishes between +public+, +protected+ and +private+ methods,
 where the default call-protection is +protected+.
 
-=========================================== 
+===========================================
 A *public* method can be called from every context. A *protected*
 method can only be invoked from the same object. A *private* method
 can only be invoked from methods defined on the same entity
@@ -1145,7 +1145,7 @@
   :private method helper {a b} {expr {$a + $b}}
   :public method foo     {a b} {: -local helper $a $b}
 }
-    
+
 nx::Class create Sub -superclass Base {
   :public method bar     {a b} {: -local helper $a $b}
   :private method helper {a b} {expr {$a * $b}}
@@ -1185,7 +1185,7 @@
 unintended interactions. The variable should be accessed via the
 private accessor, which can be invoked with the +-local+ flag.  In the
 following example class +D+ introduces a private property with the
-same name as a property in the superclass. 
+same name as a property in the superclass.
 
 [[xmp-private-properties]]
 .Listing {counter:figure-number}: Private Properties
@@ -1201,19 +1201,19 @@
 
 #
 # Define a subclass D with a private property "x"
-# and a method bar, which is capable of accessing 
+# and a method bar, which is capable of accessing
 # the private property.
 #
 nx::Class create D -superclass C {
   :property -accessor private {x d}
   :public method bar {p} {return [: -local $p get]}
 }
- 
+
 #
 # The private and public (or protected) properties
 # define internally separate variable that do not
 # conflict.
-# 
+#
 D create d1
 puts [d1 x get]   ;# prints "c"
 puts [d1 bar x]   ;# prints "d"
@@ -1228,7 +1228,7 @@
 
 As defined above, a method is a subroutine defined on an object or
 class. This object (or class) contains the method. If the object (or
-class) is deleted, the contained methods will be deleted as well. 
+class) is deleted, the contained methods will be deleted as well.
 
 ==== Instance Methods
 
@@ -1270,7 +1270,7 @@
 The following example defines an object method +bar+ on the
 instance +c1+ of class +C+, and as well as the object specific method
 +baz+ defined on the object +o1+. An object method is defined
-via +object method+. 
+via +object method+.
 
 Note that we can define a object method that shadows (redefines)
 for this object methods provided from classes.
@@ -1346,15 +1346,15 @@
 # therefore applicable on instance "c1"
 c1 foo
 
-# When trying to invoke the class method on the 
+# When trying to invoke the class method on the
 # instance, an error will be raised.
 c1 bar
 --------------------------------------------------
 
 In some other object oriented programming languages, class methods
 are called "static methods".
 
-=== Ensemble Methods 
+=== Ensemble Methods
 
 NX provides _ensemble methods_ as a means to structure the method name
 space and to group related methods. Ensemble methods are similar in
@@ -1405,13 +1405,13 @@
 [align="center"]
 ++++
 Per-object Mixins -> Per-class Mixins -> Object -> Intrinsic Class Hierarchy
-++++ 
+++++
 
 In the case, no mixins are involved, first the object is searched for
 an object method with the given name, and then the class hierarchy
 of the object. The method can be defined multiple times on the search
 path, so some of these method definitions might be _shadowed_ by the
-more specific definitions. 
+more specific definitions.
 
 
 [[xmp-method-resolution]]
@@ -1420,19 +1420,19 @@
 [source,tcl,numbers]
 --------------------------------------------------
 nx::Class create C {
-  :public method foo {} { 
+  :public method foo {} {
     return "C foo: [next]"
   }
 }
 
 nx::Class create D -superclass C {
 
-  :public method foo {} { 
+  :public method foo {} {
     return "D foo: [next]"
   }
 
    :create d1 {
-     :public object method foo {} { 
+     :public object method foo {} {
        return "d1 foo: [next]"
      }
    }
@@ -1478,13 +1478,13 @@
 
 #
 # "d1" is created based on the definitions of the last example
-# 
+#
 # Add the methods from "M1" as per-object mixin to "d1"
-d1 object mixin add M1
+d1 object mixins add M1
 
 #
 # Add the methods from "M2" as per-class mixin to class "C"
-C mixin add M2
+C mixins add M2
 
 # Invoke the method foo
 d1 foo
@@ -1511,8 +1511,8 @@
 --------------------------------------------------
 #
 # "d1" is created based on the definitions of the last two examples,
-# the mixins "M1" and "M2" are registered. 
-# 
+# the mixins "M1" and "M2" are registered.
+#
 # Define a public object method "bar", which calls the method
 # "foo" which various invocation options:
 #
@@ -1533,7 +1533,7 @@
 next three calls show how to provide flags that influence the method
 resolution. The flags can be provided between the colon and the method
 name. These flags are used rather seldomly but can be helpful in some
-situations. 
+situations.
 
 The invocation flag +-local+ means that the method has to be resolved
 from the same place, where the current method is defined. Since the
@@ -1545,7 +1545,7 @@
 
 The invocation flag +-intrinsic+ means that the method has to be resolved
 from the intrinsic definitions, meaning simply without mixins. The
-effect is here the same as with the invocation flag +-local+. 
+effect is here the same as with the invocation flag +-local+.
 
 The invocation flag +-system+ means that the method has to be resolved
 from basic - typically predefined - classes of the object system. This
@@ -1556,9 +1556,9 @@
 
 The output of <<xmp-method-resolution3,{xmp-method-resolution3}>> is:
 ----
-   M1 foo: M2 foo: d1 foo: D foo: C foo: 
-   d1 foo: D foo: C foo: 
-   d1 foo: D foo: C foo: 
+   M1 foo: M2 foo: d1 foo: D foo: C foo:
+   d1 foo: D foo: C foo:
+   d1 foo: D foo: C foo:
    ::d1: unable to dispatch method 'foo'
 ----
 
@@ -1567,7 +1567,7 @@
 
 NX provides a generalized mechanism for passing values to either
 methods (we refer to these as _method parameters_) or to objects
-(these are called _configure parameters_). Both kind of parameters 
+(these are called _configure parameters_). Both kind of parameters
 might have different features, such as:
 
 - Positional and non-positional parameters
@@ -1616,7 +1616,7 @@
   }
 
   #
-  # Method baz has non-positional and 
+  # Method baz has non-positional and
   # positional parameters:
   #
   :public object method baz {-x -y a} {
@@ -1722,7 +1722,7 @@
 {xmp-optional-req}>> with one required and one optional non-positional
 parameter. The parameter definition +-y:optional+ is equivalent to
 +-y+, since non-positional parameter are per default optional.
-However, the non-positional parameter +-x:required+ is required. If we 
+However, the non-positional parameter +-x:required+ is required. If we
 invoke +bar+ without it, the system will raise an exception.
 
 ==== Default Values for Parameters
@@ -1783,7 +1783,7 @@
 they can be used also at any time during bootstrap of an object
 system, at a time, when e.g. no objects or methods are defined. The
 same checkers are used as well for all C-implemented primitives of NX
-and the Next Scripting Framework. 
+and the Next Scripting Framework.
 
 [[img-value-checkers]]
 image::value-checkers.png[align="center",title="General Applicable Value Checkers in NX"]
@@ -1914,7 +1914,7 @@
 }
 
 #
-# Create an application class D 
+# Create an application class D
 # using the new value checkers
 #
 nx::Class create D {
@@ -1928,13 +1928,13 @@
 
 D create d1
 
-# testing "groupsize"; 
+# testing "groupsize";
 # the second call (with value 10) will raise an exception:
-d1 foo 2 
+d1 foo 2
 d1 foo 10
 
 # testing "choice"
-# the second call (with value pink for parameter a) 
+# the second call (with value pink for parameter a)
 # will raise an exception:
 d1 bar green good
 d1 bar pink bad
@@ -1971,7 +1971,7 @@
 
 *****************************************************************************
 *Multiplicity* is used to define whether a parameter should receive
-single or multiple values. 
+single or multiple values.
 *****************************************************************************
 
 A multiplicity specification has a lower and an upper bound. A lower
@@ -1996,23 +1996,23 @@
 nx::Object create o6 {
 
   #
-  # Positional parameter with an possibly empty 
+  # Positional parameter with an possibly empty
   # single value
   #
   :public object method foo {x:integer,0..1} {
     puts "x=$x"
   }
 
   #
-  # Positional parameter with an possibly empty 
+  # Positional parameter with an possibly empty
   # list of values value
   #
   :public object method bar {x:integer,0..n} {
     puts "x=$x"
   }
 
   #
-  # Positional parameter with a non-empty 
+  # Positional parameter with a non-empty
   # list of values
   #
   :public object method baz {x:integer,1..n} {
@@ -2093,7 +2093,7 @@
 [source,tcl,numbers]
 --------------------------------------------------
 #
-# Define a class Person with properties "name" 
+# Define a class Person with properties "name"
 # and "birthday"
 #
 nx::Class create Person {
@@ -2102,7 +2102,7 @@
 }
 
 #
-# Define a class Student as specialization of Person 
+# Define a class Student as specialization of Person
 # with and additional property
 #
 nx::Class create Student -superclass Person {
@@ -2151,10 +2151,10 @@
 properties, also NX provides some predefined definitions. Since
 +Person+ is a subclass of +nx::Object+ also the configure parameters of
 +nx::Object+ are inherited. In the introductory stack example, we used
-+-mixin+ applied to an object to denote per-object mixins (see
-<<xmp-using-class-safety, {xmp-using-class-safety}>>). Since +mixin+
++-mixins+ applied to an object to denote per-object mixins (see
+<<xmp-using-class-safety, {xmp-using-class-safety}>>). Since +mixins+
 is defined as a parameter on +nx::Object+ it can be used as an object
-parameter +-mixin+ for all objects in NX. To put it in other words,
+parameter +-mixins+ for all objects in NX. To put it in other words,
 every object can be configured to have per-object mixins. If we would
 remove this definition, this feature would be removed as well.
 
@@ -2173,31 +2173,31 @@
 {set:xmp-object-parameter-list:Listing {figure-number}}
 [source,tcl,numbers]
 --------------------------------------------------
-Configure parameters for Person p1: 
-   Command:   
+Configure parameters for Person p1:
+   Command:
       p1 info lookup syntax configure
-   Result: 
-      -name /value/ ?-birthday /value/? ?-object-mixin /mixinreg .../? 
-      ?-class /class/? ?-object-filter /filterreg .../? ?/__initblock/?
+   Result:
+      -name /value/ ?-birthday /value/? ?-object-mixins /mixinreg .../?
+      ?-class /class/? ?-object-filters /filterreg .../? ?/__initblock/?
 
 Configure parameter for Student s1:
-   Command:   
+   Command:
       s1 info lookup syntax configure
-   Result: 
-      ?-oncampus /boolean/? -matnr /value/ -name /value/ 
-      ?-birthday /value/? ?-object-mixin /mixinreg .../? ?-class /class/?
-      ?-object-filter /filterreg .../? ?/__initblock/?
+   Result:
+      ?-oncampus /boolean/? -matnr /value/ -name /value/
+      ?-birthday /value/? ?-object-mixins /mixinreg .../? ?-class /class/?
+      ?-object-filters /filterreg .../? ?/__initblock/?
 --------------------------------------------------
 
-The given paramter show, how (a) objects can be configured 
-at runtime or (b) how new instances can be configured 
+The given paramter show, how (a) objects can be configured
+at runtime or (b) how new instances can be configured
 at creation time via the +new+ or +create+ methods.
 Introspection can be used to obtain the configuration
 parameters from an object via
-+p1 info lookup parameters configure+ 
++p1 info lookup parameters configure+
 (returning the configure parameters currently applicable for
 +configure+ or +cget+) or from a class
-+Person info lookup parameters create+ on a class 
++Person info lookup parameters create+ on a class
 (returning the configure parameters applicable when an object
 of this class is created)
 
@@ -2217,16 +2217,16 @@
 non-positional configure parameter +-superclass+. If no superclass is
 specified for a class, the default superclass is
 +nx::Object+. Therefore +nx::Object+ is the default value for the
-parameter +superclass+. 
+parameter +superclass+.
 
-Another frequently used parameter for classes is +-mixin+ to denote
+Another frequently used parameter for classes is +-mixins+ to denote
 per-class mixins (see e.g. the introductory Stack example in
 <<xmp-class-safestack,{xmp-class-safestack}>>), which is defined in
 the same way.
 
 Since +Student+ is an instance of the meta-class +nx::Class+ it
 inherits the configure parameters from +nx::Class+ (see class diagram
-<<img-configure-parameters,{img-configure-parameters}>>). 
+<<img-configure-parameters,{img-configure-parameters}>>).
 Therefore, one can use e.g. +-superclass+ in the definition of classes.
 
 Since +nx::Class+ is a subclass of +nx::Object+, the meta-class
@@ -2244,12 +2244,12 @@
 [source,tcl,numbers]
 --------------------------------------------------
 Configure parameter for class nx::Class
-   Command:   
+   Command:
       nx::Class info lookup syntax configure
-   Result: 
-      ?-superclass /class .../? ?-mixin /mixinreg .../? 
-      ?-filter /filterreg .../? ?-object-mixin /mixinreg .../? 
-      ?-class /class/? ?-object-filter /filterreg .../? ?/__initblock/?
+   Result:
+      ?-superclass /class .../? ?-mixins /mixinreg .../?
+      ?-filters /filterreg .../? ?-object-mixins /mixinreg .../?
+      ?-class /class/? ?-object-filters /filterreg .../? ?/__initblock/?
 --------------------------------------------------
 
 ==== User defined Parameter Types
@@ -2299,7 +2299,7 @@
 Object and classes might be equipped
 with a method +unknown+ which is called in cases, where an unknown
 method is called. The method unknown receives as first argument the
-called method followed by the provided arguments 
+called method followed by the provided arguments
 
 [[xmp-unknown-method]]
 .Listing {counter:figure-number}: Unknown Method Handler
@@ -2349,11 +2349,11 @@
 ::nx::Object create o {
   # The class M is unknown at this point
 
-  :object mixin add M
-  # The line above has triggered the unknown class handler, 
+  :object mixins add M
+  # The line above has triggered the unknown class handler,
   # class M is now defined
 
-  puts [:info object mixin classes]
+  puts [:info object mixins]
   # The output will be:
   #     ***** __unknown called with <::M>
   #     ::M