Requirement: pre-filter products by customer group name to product attribute. I was looking for the “proper” way of filtering items by multiple custom attribute settings, but couldn’t find out how. So, the following is a brief explanation of how I’ve got this running in Magento 1.4.1. There are two ways of editing core code in Magento. Wrong: edit files directly in app/code/core/Mage Right: extend modules and keep them in app/code/local/MyDevCompany If you’re in a hurry, you might edit core files directly and then later copy the altered code out into correctly extended module files.