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+<p><br>
+<h2>Data handling in Simulink</h2><hr>
+
+	Since SIMULINK can only send among blocks a limited set of object types (that is, inside Simulink lines can only travel numbers,
+    vectors or Simulink defined signals), <b>the main concept about LTPDA GUI and LTPDA Simulink models is that what's passed among
+    blocks is not a true LTPDA object (an AO, a filter, a specwin or so), but rather a pure number, intended as an index inside a
+    given array of objects.</b><br><br>
+    
+    Every analysis block in a LTPDA model produces the output of its calculation, then stores this output into a global array - which will be
+    accessible by all following functions/blocks - and send back to Simulink just the index of this newly added object inside the array.
+    <br><br>
+    For example:</p><br><br>
+  <img src="images/model_2.png" alt="A simple analysis" border="1">
+  <br>
+  <br>
+<p>
+    <b>The first block</b> load create an AO from a file on disk. This AO is saved in a global array: assuming the array was empty, this is
+    the 1st object, so '1' is the number sent by the first block into Simulink.<br>
+    <b>The second block</b> receives this '1': the corresponding (1st) object is retrieved from the array, then the analysis function (<tt>pwelch</tt>) is applied.
+    The output is appended back into the array, as 2nd element. So, '2' is the content of the signal leaving the second block.<br>
+    <b>The third block</b> receives '2', retrieves the corresponding (2nd) object from the array and produces a plot of it.
+    <br><br>
+    Thus, during the analysis cycle the array of objects becomes populated: unless differently set, all the temporary objects created
+    during the analysis will be canceled at the end of the analisys itself.
+    
+    <br><br><br>
+    
+    The LTPDA GUI is based on two global arrays: 
+	<ul>
+ 		<li> The aforementioned '<b>Input array</b>', which encloses all the LTPDA objects created by the user (for example,
+            loading from file) and the objects generated during the analysis.<br>This is shown into the main panel of the LTPDA GUI.<br></li>
+  	    <li> The '<b>Output array</b>', meant as a way to separate primary objectives of the analysis from the
+    other - working - objects, contained in the Input array.<br>This is shown into its own panel, the Output panel.</li>
+	</ul>
+
+    The only way to save an object into the Output array is using the proper 'Send to Output' block, which will copy the object
+    passed from the Input to the Output array.<br>
+    <br><br>
+    <h2>Parameters</h2><hr>
+    
+    In order to enclose all the parameters of each block together with the Simulink model file, each parameters list is converted
+    into a string and saved into the Block Description, a specific field of every block in Simulink.<br>
+    Every time the user selects a block inside a valid LTPDA model the LTPDA GUI will automatically read this description to convert
+    it back to a proper plist. 'Valid' LTPDA models are those created by the GUI, thus containing the short annotation with the
+    author's name, time and date of creation and so on.<br><br>
+
+    For more information on parameters handling, see the paragraph regarding the Parameters panel. <br><br><br>
+    
+</p>
+