diff --git a/doc/devel/UML/builder.violet b/doc/devel/UML/builder.violet
new file mode 100644
index 0000000..7144907
--- /dev/null
+++ b/doc/devel/UML/builder.violet
@@ -0,0 +1,530 @@
+<?xml version="1.0" encoding="UTF-8"?> 
+<java version="1.6.0" class="java.beans.XMLDecoder"> 
+ <object class="com.horstmann.violet.ClassDiagramGraph"> 
+  <void method="addNode"> 
+   <object id="InterfaceNode0" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="methods"> 
+     <void property="text"> 
+      <string>get_root()
+get_from_path(char *)</string> 
+     </void> 
+    </void> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+Filesystem</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>239.65022612023944</double> 
+     <double>428.68019298068566</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode0" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>MountedFilesytem</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>115.78546881025578</double> 
+     <double>581.4909858656838</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode1" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>IsoImage</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>377.65022612023944</double> 
+     <double>579.6801929806866</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="InterfaceNode1" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="methods"> 
+     <void property="text"> 
+      <string>lstat()
+read()
+close()
+open()</string> 
+     </void> 
+    </void> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+SourceFile</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>482.9740126701578</double> 
+     <double>408.11257163567745</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode2" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>TarFile</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>269.92071150027203</double> 
+     <double>579.4370214406978</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="InterfaceNode2" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="methods"> 
+     <void property="text"> 
+      <string>read()
+size()
+open()
+close()</string> 
+     </void> 
+    </void> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+Stream</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>781.3090745567881</double> 
+     <double>275.3064215363851</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode3" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>FdStream</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>919.2570998971042</double> 
+     <double>440.60621052176435</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode4" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>FileStream</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>650.496291906489</double> 
+     <double>438.22779629175875</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode5" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>TransformStream</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>771.7954176367664</double> 
+     <double>441.79541763676707</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="InterfaceNode3" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="methods"> 
+     <void property="text"> 
+      <string>create_file()
+create_symlink()
+create_dir()</string> 
+     </void> 
+    </void> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+TreeNodeBuilder</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>470.92601754107767</double> 
+     <double>54.86674707528562</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode6" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>TreeNode</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>778.9306603267822</double> 
+     <double>72.70485380032646</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode7" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>File</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>777.7414532117795</double> 
+     <double>170.0566174453891</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode8" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>Dir</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>902.6082002870654</double> 
+     <double>168.86741033038638</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="ClassNode9" class="com.horstmann.violet.ClassNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>Symlink</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>660.0099488265103</double> 
+     <double>172.43503167539455</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="InterfaceNode4" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+FileBuilder</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>70.16321978516044</double> 
+     <double>171.2458245603918</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="InterfaceNode5" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+DirBuilder</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>191.46234551543796</double> 
+     <double>171.24582456039184</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="addNode"> 
+   <object id="InterfaceNode6" class="com.horstmann.violet.InterfaceNode"> 
+    <void property="name"> 
+     <void property="text"> 
+      <string>«interface»
+SymlinkBuilder</string> 
+     </void> 
+    </void> 
+   </object> 
+   <object class="java.awt.geom.Point2D$Double"> 
+    <void method="setLocation"> 
+     <double>305.62622855569924</double> 
+     <double>171.2458245603918</double> 
+    </void> 
+   </object> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="InterfaceNode0"/> 
+   <object idref="InterfaceNode1"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode5"/> 
+   <object idref="InterfaceNode2"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode4"/> 
+   <object idref="InterfaceNode2"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode3"/> 
+   <object idref="InterfaceNode2"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode0"/> 
+   <object idref="InterfaceNode0"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode2"/> 
+   <object idref="InterfaceNode0"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode1"/> 
+   <object idref="InterfaceNode0"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="HVH"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode4"/> 
+   <object idref="InterfaceNode1"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+    <void property="middleLabel"> 
+     <string>{{create}}</string> 
+    </void> 
+   </object> 
+   <object idref="InterfaceNode3"/> 
+   <object idref="ClassNode6"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode9"/> 
+   <object idref="ClassNode6"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode7"/> 
+   <object idref="ClassNode6"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="VHV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="TRIANGLE"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode8"/> 
+   <object idref="ClassNode6"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="HVH"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+   </object> 
+   <object idref="ClassNode7"/> 
+   <object idref="InterfaceNode2"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="HV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+    <void property="startArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="BLACK_DIAMOND"/> 
+    </void> 
+   </object> 
+   <object idref="InterfaceNode3"/> 
+   <object idref="InterfaceNode6"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="HV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+    <void property="startArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="BLACK_DIAMOND"/> 
+    </void> 
+   </object> 
+   <object idref="InterfaceNode3"/> 
+   <object idref="InterfaceNode5"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="bentStyle"> 
+     <object class="com.horstmann.violet.BentStyle" field="HV"/> 
+    </void> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+    <void property="startArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="BLACK_DIAMOND"/> 
+    </void> 
+   </object> 
+   <object idref="InterfaceNode3"/> 
+   <object idref="InterfaceNode4"/> 
+  </void> 
+  <void method="connect"> 
+   <object class="com.horstmann.violet.ClassRelationshipEdge"> 
+    <void property="endArrowHead"> 
+     <object class="com.horstmann.violet.ArrowHead" field="V"/> 
+    </void> 
+    <void property="lineStyle"> 
+     <object class="com.horstmann.violet.LineStyle" field="DOTTED"/> 
+    </void> 
+   </object> 
+   <object idref="InterfaceNode3"/> 
+   <object idref="InterfaceNode1"/> 
+  </void> 
+ </object> 
+</java> 
diff --git a/doc/devel/UML/builder.violet.png b/doc/devel/UML/builder.violet.png
new file mode 100644
index 0000000..6a6c7a6
Binary files /dev/null and b/doc/devel/UML/builder.violet.png differ