diff --git a/.gitignore b/.gitignore
index 4b0c6de..8b34f04 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,6 @@ composer.phar
 
 # translations
 *.mo
+
+# general
+.DS_Store
diff --git a/Behavioral/Command/AddMessageDateCommand.php b/Behavioral/Command/AddMessageDateCommand.php
index e37d0dd..74fc441 100644
--- a/Behavioral/Command/AddMessageDateCommand.php
+++ b/Behavioral/Command/AddMessageDateCommand.php
@@ -7,7 +7,7 @@ namespace DesignPatterns\Behavioral\Command;
  * This concrete command tweaks receiver to add current date to messages
  * invoker just knows that it can call "execute"
  */
-class AddMessageDateCommand implements UndoableCommandInterface
+class AddMessageDateCommand implements UndoableCommand
 {
     /**
      * @var Receiver
diff --git a/Behavioral/Command/CommandInterface.php b/Behavioral/Command/Command.php
similarity index 89%
rename from Behavioral/Command/CommandInterface.php
rename to Behavioral/Command/Command.php
index db98ef7..9330359 100644
--- a/Behavioral/Command/CommandInterface.php
+++ b/Behavioral/Command/Command.php
@@ -3,7 +3,7 @@ declare(strict_types=1);
 
 namespace DesignPatterns\Behavioral\Command;
 
-interface CommandInterface
+interface Command
 {
     /**
      * this is the most important method in the Command pattern,
diff --git a/Behavioral/Command/HelloCommand.php b/Behavioral/Command/HelloCommand.php
index b5eb316..8b088d1 100644
--- a/Behavioral/Command/HelloCommand.php
+++ b/Behavioral/Command/HelloCommand.php
@@ -7,7 +7,7 @@ namespace DesignPatterns\Behavioral\Command;
  * This concrete command calls "print" on the Receiver, but an external
  * invoker just knows that it can call "execute"
  */
-class HelloCommand implements CommandInterface
+class HelloCommand implements Command
 {
     /**
      * @var Receiver
diff --git a/Behavioral/Command/Invoker.php b/Behavioral/Command/Invoker.php
index 8c0e3a0..7e1f41e 100644
--- a/Behavioral/Command/Invoker.php
+++ b/Behavioral/Command/Invoker.php
@@ -10,7 +10,7 @@ namespace DesignPatterns\Behavioral\Command;
 class Invoker
 {
     /**
-     * @var CommandInterface
+     * @var Command
      */
     private $command;
 
@@ -18,9 +18,9 @@ class Invoker
      * in the invoker we find this kind of method for subscribing the command
      * There can be also a stack, a list, a fixed set ...
      *
-     * @param CommandInterface $cmd
+     * @param Command $cmd
      */
-    public function setCommand(CommandInterface $cmd)
+    public function setCommand(Command $cmd)
     {
         $this->command = $cmd;
     }
diff --git a/Behavioral/Command/README.rst b/Behavioral/Command/README.rst
index 1c83577..0af4642 100644
--- a/Behavioral/Command/README.rst
+++ b/Behavioral/Command/README.rst
@@ -38,9 +38,9 @@ Code
 
 You can also find this code on `GitHub`_
 
-CommandInterface.php
+Command.php
 
-.. literalinclude:: CommandInterface.php
+.. literalinclude:: Command.php
    :language: php
    :linenos:
 
@@ -72,4 +72,4 @@ Tests/CommandTest.php
    :linenos:
 
 .. _`GitHub`: https://github.com/domnikl/DesignPatternsPHP/tree/master/Behavioral/Command
-.. __: http://en.wikipedia.org/wiki/Command_pattern
\ No newline at end of file
+.. __: http://en.wikipedia.org/wiki/Command_pattern
diff --git a/Behavioral/Command/UndoableCommandInterface.php b/Behavioral/Command/UndoableCommand.php
similarity index 76%
rename from Behavioral/Command/UndoableCommandInterface.php
rename to Behavioral/Command/UndoableCommand.php
index 491d695..ce8de92 100644
--- a/Behavioral/Command/UndoableCommandInterface.php
+++ b/Behavioral/Command/UndoableCommand.php
@@ -3,7 +3,7 @@ declare(strict_types=1);
 
 namespace DesignPatterns\Behavioral\Command;
 
-interface UndoableCommandInterface extends CommandInterface
+interface UndoableCommand extends Command
 {
     /**
      * This method is used to undo change made by command execution
diff --git a/Behavioral/Command/uml/Command.uml b/Behavioral/Command/uml/Command.uml
index 368d5f0..80f06ec 100644
--- a/Behavioral/Command/uml/Command.uml
+++ b/Behavioral/Command/uml/Command.uml
@@ -1,28 +1,42 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Diagram>
-  <ID>PHP</ID>
-  <OriginalElement>\DesignPatterns\Behavioral\Command\HelloCommand</OriginalElement>
-  <nodes>
-    <node x="185.0" y="15.0">\DesignPatterns\Behavioral\Command\Invoker</node>
-    <node x="0.0" y="97.0">\DesignPatterns\Behavioral\Command\HelloCommand</node>
-    <node x="189.0" y="139.0">\DesignPatterns\Behavioral\Command\Receiver</node>
-    <node x="10.0" y="0.0">\DesignPatterns\Behavioral\Command\CommandInterface</node>
-  </nodes>
-  <notes />
-  <edges>
-    <edge source="\DesignPatterns\Behavioral\Command\HelloCommand" target="\DesignPatterns\Behavioral\Command\CommandInterface">
-      <point x="0.0" y="-44.5" />
-      <point x="0.0" y="23.5" />
-    </edge>
-  </edges>
-  <settings layout="Hierarchic Group" zoom="1.0" x="171.0" y="93.0" />
-  <SelectedNodes />
-  <Categories>
-    <Category>Fields</Category>
-    <Category>Constants</Category>
-    <Category>Constructors</Category>
-    <Category>Methods</Category>
-  </Categories>
-  <VISIBILITY>private</VISIBILITY>
-</Diagram>
-
+<?xml version="1.0" encoding="UTF-8"?>
+<Diagram>
+  <ID>PHP</ID>
+  <OriginalElement>\DesignPatterns\Behavioral\Command\AddMessageDateCommand</OriginalElement>
+  <nodes>
+    <node x="0.0" y="246.0">\DesignPatterns\Behavioral\Command\AddMessageDateCommand</node>
+    <node x="22.5" y="123.0">\DesignPatterns\Behavioral\Command\UndoableCommand</node>
+    <node x="124.75" y="0.0">\DesignPatterns\Behavioral\Command\Command</node>
+    <node x="0.0" y="409.0">\DesignPatterns\Behavioral\Command\Invoker</node>
+    <node x="177.5" y="100.0">\DesignPatterns\Behavioral\Command\HelloCommand</node>
+    <node x="402.5" y="0.0">\DesignPatterns\Behavioral\Command\Receiver</node>
+  </nodes>
+  <notes />
+  <edges>
+    <edge source="\DesignPatterns\Behavioral\Command\HelloCommand" target="\DesignPatterns\Behavioral\Command\Command">
+      <point x="0.0" y="-48.0" />
+      <point x="267.5" y="75.0" />
+      <point x="205.75" y="75.0" />
+      <point x="27.0" y="25.0" />
+    </edge>
+    <edge source="\DesignPatterns\Behavioral\Command\UndoableCommand" target="\DesignPatterns\Behavioral\Command\Command">
+      <point x="0.0" y="-25.0" />
+      <point x="90.0" y="75.0" />
+      <point x="151.75" y="75.0" />
+      <point x="-27.0" y="25.0" />
+    </edge>
+    <edge source="\DesignPatterns\Behavioral\Command\AddMessageDateCommand" target="\DesignPatterns\Behavioral\Command\UndoableCommand">
+      <point x="0.0" y="-59.0" />
+      <point x="0.0" y="25.0" />
+    </edge>
+  </edges>
+  <settings layout="Hierarchic Group" zoom="1.0" x="145.0" y="200.5" />
+  <SelectedNodes />
+  <Categories>
+    <Category>Fields</Category>
+    <Category>Constants</Category>
+    <Category>Constructors</Category>
+    <Category>Methods</Category>
+  </Categories>
+  <VISIBILITY>private</VISIBILITY>
+</Diagram>
+
diff --git a/Behavioral/Command/uml/uml.png b/Behavioral/Command/uml/uml.png
index d021750..e95b5ea 100644
Binary files a/Behavioral/Command/uml/uml.png and b/Behavioral/Command/uml/uml.png differ