I am trying to learn about creating modules by looking at the core code to see how the directory structure is formatted. I was looking at the Magento 1.9 sales module.
In the adminhtml.xml file, The mage_sales module has children which each have their own action. These actions contain 'adminhtml/sales_order' or 'sales_invoice' for example. How is this method accessed? I thought because it depends on Mage_Sales, this means in the Mage/Sales directory and then the action implies the directory of where that method that's being called. So i assumed it would be in Mage/Sales/Block/adminhtml/'and be here'.
I just want to understand where these actions are located and how they are being called as I can't find them and I would like to know how Magento structures their modules so I have some guidelines to follow by looking at their code.