These functions are assumed to be globally available to all scripts (they aren't defined in the available Lua files, or are defined in files that are known to be always loaded).
This list is assumed incomplete; additional functions could exist in the exe but not be used in the game scripts, and there's no definitive list of Lua files that are always loaded.
These functions are defined in Lua files that aren't always loaded. They're probably only available in the file that defined them or by including that file in another script.