The Product Delivery Team keeps track of bugs that most affect the usability of the browser. The idea is that after the PDT bugs are fixed, Mozilla will have reached dogfood. That is, it will be usable enough for developers and testers to use every day as their main browser and mail client even if it isn't perfect yet. Bugs are marked [ Dogfood] when someone believes that the bug keeps Mozilla from being usable as dogfood. The PDT team marks the bug [PDT+] if they agree and [PDT-] if not.