These are the localization files for Factorization. I haven't gotten around to adding localization support to various GUI and notification messages, but all items & blocks should have localizations at least. Let me know if there is anything specific need you a key for.
Using ".hint" instead of ".name" in a localization entry will add hint text to the item, which will be rendered in light gray italics underneath the item name. ".shift" entries will only show up while the player is holding shift, and are rendered in dark gray italics. Additionally, \n will be replaced with line breaks.
Always use the en_US.lang file as the origin of your entries, this is the most up-to-date file!
Keep in mind these files HAVE to be UTF-8 encoded, anything else will NOT work!