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            This is a file from the  Wikimedia Commons. Information from its  description page there is shown below.  Commons is a freely licensed media file repository.  You can help. 
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           | Description | 
           created by Isaac Yonemoto using Inkscape | 
          
          
           | Date | 
           2006-03-24 (first version); 2006-03-26 (last version) | 
          
          
           | Source | 
           Originally from  en.wikipedia; description page is/was  here. | 
          
          
           | Author | 
           Original uploader was  Takometer at  en.wikipedia | 
          
          
           Permission ( Reusing this file) | 
           
             CC-BY-2.5. 
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          This diagram image could be recreated using  vector graphics as an  SVG file. This has several advantages; see  Commons:Media for cleanup for more information. If an SVG form of this image is already available, please upload it. After uploading an SVG, replace this template with {{ vector version available|new image name.svg}}. | 
         
        
         Licensing 
        
         
           
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          This file is licensed under the  Creative Commons  Attribution 2.5 Generic license. | 
          
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            - You are free: 
              - to share – to copy, distribute and transmit the work
 
              - to remix – to adapt the work
 
              
             
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           http://creativecommons.org/licenses/by/2.5 CC-BY-2.5 Creative Commons Attribution 2.5 truetrue 
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       File usage
       
        The following pages on Schools Wikipedia link to this image (list may be incomplete):