title: Magento - locate specific core files
body: <p>I am familiar with theming and using template hints in the Magento back office to locate .phtml files.</p>
  
  <p>What I am not really familiar with are the core files such as app/code/core/Mage/Catalog/Model</p>
  
  <p>What I need to do is override a core file like I would a core phtml file by copying it to 'my theme'.</p>
  
  <p>I basically want to amend some labels which appear on the order summary page of the Magento checkout process - domain.com/checkout/cart/</p>
  
  <p>I followed the trail to the phtml files using template hints. Within the app/design/frontend/default/mytheme/template/checkout/cart I found the code</p>
  
  renderTotals(); ?>
  
  <p>Now I managed, by accident, to stumble upon two of the files I wanted to change:</p>
  
  <p>/httpdocs/app/code/local/Mage/Sales/Model/Quote/Address/Total/Grand.php
  /httpdocs/app/code/local/Mage/Sales/Model/Quote/Address/Total/Shipping.php</p>
  
  <p>I made local copies of these files (<a href="http://www.magentocommerce.com/wiki/how_to/how_to_create_a_local_copy_of_app_code_core_mage" rel="nofollow noreferrer">http://www.magentocommerce.com/wiki/how_to/how_to_create_a_local_copy_of_app_code_core_mage</a>) to override the default labels, like I would if I was overriding a template file.</p>
  
  <p>My question is, how can you locate core files which pertain to the 'stuff' you want to change, located in function calls such as renderTotals(); ?> in the phtml files?</p>
  
  <p>Not being able to pinpoint stuff like I can with template hints is slowing me down, and I am struggling to find a solution as I am not up on all the vocab surrounding Magento yet.</p>
  
  <p>Hope this makes sense and thanks in advance!</p>