"F5" is the keyboard function key used in the free-to-play game C-evo to display in a pop-up window all the Foreign Unit Designs your nation is aware of. They are listed in groups, such as "fast army units", "slow army units", and ships, generally showing the latest at the top of each group. Names are usually generic but may add a nation name for distinction, e.g. "Greek Marines". Clicking any name tells you its specifications and how many you have defeated and how many remainders you are aware of.