diff --git a/description.lua b/description.lua
index 1ed88ee..a37a77f 100644
--- a/description.lua
+++ b/description.lua
@@ -1,8 +1,7 @@
-version = "0.1"
+version = "0.2"
 license = "GPL"
 package = "sysdyn"
 title = "System Dynamics"
-date = "17 July 2015"
 authors = "Gilberto Camara and Pedro R. Andrade"
 contact = "pedro.andrade@inpe.br"
 content = "Implements a System Dynamics framework."
diff --git a/doc/files/SysDynModel.html b/doc/files/SysDynModel.html
index c7482dd..4fa0578 100644
--- a/doc/files/SysDynModel.html
+++ b/doc/files/SysDynModel.html
@@ -62,6 +62,8 @@ <h1>sysdyn</h1>
 		
 			
 		
+	
+		
 	
 		
 	
@@ -92,6 +94,8 @@ <h1><a href="../files/models.html">Models</a></h1>
 		
 			
 		
+	
+		
 	
 
 	
@@ -110,6 +114,7 @@ <h1>Types</h1>
 				
 			
 		
+		
 	</ul>
 
 
@@ -131,6 +136,8 @@ <h1>Types</h1>
 	
 		
 	
+		
+	
 
 	
 
@@ -143,6 +150,7 @@ <h1>Types</h1>
 		
 		
 		
+		
 	</ul>
 
 
@@ -157,6 +165,9 @@ <h1><a href="../files/examples.html">Examples</a></h1>
 <!-- Data -->
 
 
+<!-- Font -->
+
+
 
 				</div> <!-- id="navigation" -->
 
@@ -196,6 +207,11 @@ <h3>Arguments</h3>
     </li> 
     
   
+    <li>
+	  <strong>deltaTime</strong>: A numeric value with the period to execute the changes of the model. The default value is one.
+    </li> 
+    
+  
     <li>
 	  <strong>graphics</strong>: A table with internal tables describing how the parameters of the model will be drawn in the screen. It can have three values:
     </li> 
@@ -254,7 +270,7 @@ <h3>Arguments</h3>
           
           
             <td>
-            A table with internal tables with the attributes to be drawn as a phase space. The first attribute of every internal table will be used as x axis.
+            A table with internal tables with the attributes to be drawn as a phase space. The first attribute of every internal table will be used as
             </td>
           
         
@@ -263,6 +279,11 @@ <h3>Arguments</h3>
       <span class="arg">
     
   
+    <li>
+	  <strong>updateTime</strong>: A numeric value with the period to update the charts. The default value is one. x axis.
+    </li> 
+    
+  
     <li>
 	  <strong>...</strong>: Any other value that can be used as parameter for the Model.
     </li> 
diff --git a/doc/files/data.html b/doc/files/data.html
index cae210b..0b498fe 100644
--- a/doc/files/data.html
+++ b/doc/files/data.html
@@ -62,6 +62,8 @@ <h1>sysdyn</h1>
 		
 			
 		
+	
+		
 	
 		
 	
@@ -92,6 +94,8 @@ <h1><a href="../files/models.html">Models</a></h1>
 		
 			
 		
+	
+		
 	
 
 	
@@ -112,6 +116,7 @@ <h1>Types</h1>
 				
 			
 		
+		
 	</ul>
 
 
@@ -133,6 +138,8 @@ <h1>Types</h1>
 	
 		
 	
+		
+	
 
 	
 
@@ -145,6 +152,7 @@ <h1>Types</h1>
 		
 		
 		
+		
 	</ul>
 
 
@@ -159,6 +167,9 @@ <h1><a href="../files/examples.html">Examples</a></h1>
 <!-- Data -->
 
 
+<!-- Font -->
+
+
 
 				</div> <!-- id="navigation" -->
 
diff --git a/doc/files/examples.html b/doc/files/examples.html
index ab48189..8e04dca 100644
--- a/doc/files/examples.html
+++ b/doc/files/examples.html
@@ -62,6 +62,8 @@ <h1>sysdyn</h1>
 		
 			
 		
+	
+		
 	
 		
 	
@@ -92,6 +94,8 @@ <h1><a href="../files/models.html">Models</a></h1>
 		
 			
 		
+	
+		
 	
 
 	
@@ -112,6 +116,7 @@ <h1>Types</h1>
 				
 			
 		
+		
 	</ul>
 
 
@@ -133,6 +138,8 @@ <h1>Types</h1>
 	
 		
 	
+		
+	
 
 	
 
@@ -145,6 +152,7 @@ <h1>Types</h1>
 		
 		
 		
+		
 	</ul>
 
 
@@ -159,9 +167,13 @@ <h1>Examples</h1>
 <!-- Data -->
 
 
+<!-- Font -->
+
+
 
 				</div> <!-- id="navigation" -->
 
+				
 				<div id="content">
 					<h1>Examples</h1>
 					
@@ -182,8 +194,19 @@ <h1>Examples</h1>
 							
 								
 							
+								
+								<tr>
+									<!-- <td class="name"><a href="files/predatorprey.html">predatorprey</a></td> -->
+									
+									
+									<td class="name"><a href = "#predatorprey">predatorprey</a></td>
+									<td class="summary">Simulation of predator-prey model.</td>
+								</tr>
+								
+							
 						</table>
 					
+					
 					<dl class="function">
 						
 							
@@ -205,6 +228,16 @@ <h1>Examples</h1>
 							
 						
 							
+							
+						
+							
+								
+								<dt><h2>predatorprey<a name="predatorprey"></h2>
+									
+
+									Simulation of predator-prey model.
+								</dt>
+							
 							
 						
 					</dl>
diff --git a/doc/files/font.html b/doc/files/font.html
new file mode 100644
index 0000000..de1d6a2
--- /dev/null
+++ b/doc/files/font.html
@@ -0,0 +1,200 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html>
+	<head>
+	    
+	    	<title>System Dynamics</title>
+	    
+	    <link rel="stylesheet" href="../luadoc.css" type="text/css" />
+		<!--meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/-->
+
+		
+
+	</head>
+
+	<body>
+		<div id="container">
+			<div id="product">
+				<div id="product_logo">
+					<a href="http://www.terrame.org">
+					<img src='../img/terrame.png'/><br/></div></a>
+				<div id="product_name"><big><b></b></big></div>
+				<div id="product_description"></div>
+			</div> <!-- id="product" -->
+
+			<div id="main">
+				<div id="navigation">
+					<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+
+
+<h1>sysdyn</h1>
+<ul>
+	
+		<li><a href="../index.html">Index</a></li>
+	
+</ul>
+
+<!-- Module list -->
+
+
+<!-- Models list -->
+
+	
+	
+		
+			
+		
+	
+		
+			
+		
+	
+		
+			
+		
+	
+		
+			
+		
+	
+		
+			
+		
+	
+		
+			
+		
+	
+		
+	
+		
+	
+
+	
+		
+			<h1><a href="../files/models.html">Models</a></h1>
+		
+	
+
+
+<!-- Types list -->
+
+	
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+			
+		
+	
+		
+	
+
+	
+		<h1>Types</h1>
+	
+
+	<ul>
+		
+		
+		
+		
+		
+		
+		
+					<li>
+						<a href="../files/SysDynModel.html">SysDynModel</a>
+					</li>
+				
+			
+		
+		
+	</ul>
+
+
+<!-- Files list -->
+
+	
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+	
+		
+	
+
+	
+
+	<ul>
+		
+		
+		
+		
+		
+		
+		
+		
+		
+	</ul>
+
+
+<!-- Examples -->
+
+	
+		<h1><a href="../files/examples.html">Examples</a></h1>
+	
+
+
+
+<!-- Data -->
+
+
+<!-- Font -->
+
+
+
+				</div> <!-- id="navigation" -->
+
+				<div id="content">
+					<h1><code>Font</code></h1>
+					
+						<table class="file_list">
+							
+						</table>
+					
+
+					<dl class="function">
+					
+					</dl>
+				</div> <!-- id="content" -->
+			</div> <!-- id="main" -->
+
+			<div id="about">
+				<p><a href="http://validator.w3.org/check?uri=referer"><img src="http://www.w3.org/Icons/valid-xhtml10" alt="Valid XHTML 1.0!" height="31" width="88" /></a></p>
+			</div> <!-- id="about" -->
+
+		</div> <!-- id="container" -->	
+	</body>
+</html>
+
diff --git a/doc/files/models.html b/doc/files/models.html
index eab354f..f108c64 100644
--- a/doc/files/models.html
+++ b/doc/files/models.html
@@ -62,6 +62,8 @@ <h1>sysdyn</h1>
 		
 			
 		
+	
+		
 	
 		
 	
@@ -92,6 +94,8 @@ <h1>Models</h1>
 		
 			
 		
+	
+		
 	
 
 	
@@ -112,6 +116,7 @@ <h1>Types</h1>
 				
 			
 		
+		
 	</ul>
 
 
@@ -133,6 +138,8 @@ <h1>Types</h1>
 	
 		
 	
+		
+	
 
 	
 
@@ -145,6 +152,7 @@ <h1>Types</h1>
 		
 		
 		
+		
 	</ul>
 
 
@@ -159,6 +167,9 @@ <h1><a href="../files/examples.html">Examples</a></h1>
 <!-- Data -->
 
 
+<!-- Font -->
+
+
 
 				</div> <!-- id="navigation" -->
 
@@ -211,6 +222,8 @@ <h1>Models</h1>
 						
 							
 						
+							
+						
 					</table>
 					<dl class="function">
 						
@@ -330,6 +343,8 @@ <h3>Arguments</h3>
 						
 							
 						
+							
+						
 					</dl>
 				</div> <!-- id="content" -->
 			</div> <!-- id="main" -->
diff --git a/doc/index.html b/doc/index.html
index 9d86476..807a618 100644
--- a/doc/index.html
+++ b/doc/index.html
@@ -62,6 +62,8 @@ <h1>sysdyn</h1>
 		
 			
 		
+	
+		
 	
 		
 	
@@ -92,6 +94,8 @@ <h1><a href="files/models.html">Models</a></h1>
 		
 			
 		
+	
+		
 	
 
 	
@@ -112,6 +116,7 @@ <h1>Types</h1>
 				
 			
 		
+		
 	</ul>
 
 
@@ -133,6 +138,8 @@ <h1>Types</h1>
 	
 		
 	
+		
+	
 
 	
 
@@ -145,6 +152,7 @@ <h1>Types</h1>
 		
 		
 		
+		
 	</ul>
 
 
@@ -159,6 +167,9 @@ <h1><a href="files/examples.html">Examples</a></h1>
 <!-- Data -->
 
 
+<!-- Font -->
+
+
 
 				</div> <!-- id="navigation" -->
 
@@ -168,13 +179,13 @@ <h1><a href="files/examples.html">Examples</a></h1>
 						</center>
 						<br>
 
-						<b>Version: </b>0.1<br>
+						<b>Version: </b>0.2<br>
 						
 
 						<b>License: </b>GPL<br>
 						
 
-						<b>Release: </b>17 July 2015<br>
+						<b>Release: </b>06 August 2015<br>
 						
 
 						<b>Authors: </b> Gilberto Camara and Pedro R. Andrade<br>
@@ -222,6 +233,8 @@ <h1><a href="files/examples.html">Examples</a></h1>
 							
 								
 							
+						
+							
 						
 							
 						
@@ -281,6 +294,8 @@ <h2><a href="files/models.html">Models</a></h2>
 							
 								
 							
+								
+							
 							</table>
 						
 					
@@ -302,6 +317,8 @@ <h2><a href="files/models.html">Models</a></h2>
 						
 							
 								
+							
+						
 							
 						
 
@@ -330,6 +347,8 @@ <h2>Types</h2>
 								</tr>
 								
 							
+								
+							
 						</table>
 					
 
@@ -349,6 +368,8 @@ <h2>Types</h2>
 							
 						
 							
+						
+							
 						
 
 						
@@ -370,6 +391,8 @@ <h2>Types</h2>
 							
 								
 							
+								
+							
 						</table>
 					
 
@@ -392,10 +415,22 @@ <h2><a href="files/examples.html">Examples</a></h2>
 							
 								
 							
+								
+									<tr>
+										<!-- <td class="name"><a href="files/predatorprey.html">predatorprey</a></td> -->
+										
+										<td class="name">predatorprey</td>
+										<td class="summary">Simulation of predator-prey model.</td>
+									</tr>
+								
+							
 						</table>
 					
 
 					
+
+					
+
 				</div> <!-- id="content" -->
 			</div> <!-- id="main" -->
 
diff --git a/doc/luadoc.css b/doc/luadoc.css
index edb8d96..350f4a2 100644
--- a/doc/luadoc.css
+++ b/doc/luadoc.css
@@ -146,7 +146,6 @@ div.header, div.footer { margin-left: 0em; }
 #navigation
 {
 	float: left;
-	position: fixed;
 	width: 12em;
 	margin: 0;
 	vertical-align: top;
@@ -249,6 +248,8 @@ table.arg_tab
 	margin-top: 1em;
 	margin-bottom: 1em;
 	text-align: left;
+	margin-right:auto;
+	margin-left:0px
 }
 
 table.module_list td
diff --git a/examples/predatorprey.lua b/examples/predatorprey.lua
index 82e317c..a1775c4 100644
--- a/examples/predatorprey.lua
+++ b/examples/predatorprey.lua
@@ -1,3 +1,4 @@
+-- @example Simulation of predator-prey model.
 
 import("sysdyn")