diff -r 282500e03dbc -r ce04d79b8e57 svghmi/svghmi.py
--- a/svghmi/svghmi.py	Tue Aug 20 10:30:59 2019 +0200
+++ b/svghmi/svghmi.py	Tue Aug 20 10:32:34 2019 +0200
@@ -9,7 +9,7 @@
 from __future__ import absolute_import
 import os
 import shutil
-from itertools import izip
+from itertools import izip, imap
 from pprint import pprint, pformat
 
 import wx
@@ -71,12 +71,33 @@
         else:
             self.children.append(node)
             
+    def etree(self):
+
+        attribs = dict(name=self.name)
+        if self.path is not None:
+            attribs["path"]=".".join(self.path)
+
+        res = etree.Element(self.nodetype, **attribs)
+
+        if hasattr(self, "children"): 
+            for child_etree in imap(lambda c:c.etree(), self.children):
+                res.append(child_etree)
+
+        return res
+
+# module scope for HMITree root
+# so that CTN can use HMITree deduced in Library
+# note: this only works because library's Generate_C is 
+#       systematicaly invoked before CTN's CTNGenerate_C
+
+hmi_tree_root = None
 
 class SVGHMILibrary(POULibrary):
     def GetLibraryPath(self):
          return paths.AbsNeighbourFile(__file__, "pous.xml")
 
     def Generate_C(self, buildpath, varlist, IECCFLAGS):
+        global hmi_tree_root
 
         """
         PLC Instance Tree:
@@ -209,6 +230,11 @@
 
         return res
 
+    def GetHMITree(self):
+        global hmi_tree_root
+        res = [hmi_tree_root.etree()]
+        return res
+
     def CTNGenerate_C(self, buildpath, locations):
         """
         Return C code generated by iec2c compiler
@@ -224,7 +250,8 @@
 
             # TODO : move to __init__
             transform = XSLTransform(os.path.join(ScriptDirectory, "gen_index_xhtml.xslt"),
-                          [("GetSVGGeometry", lambda *_ignored:self.GetSVGGeometry())])
+                          [("GetSVGGeometry", lambda *_ignored:self.GetSVGGeometry()),
+                           ("GetHMITree", lambda *_ignored:self.GetHMITree())])
 
 
             # load svg as a DOM with Etree