I'm designing a dataflow diagram and I reached a point where I don't know if I have to represent the external files that my application loads at the beggining (it's automatic, there's no entity interaction). I represented it as a data store, am I right? I guess that data store is not supposed to be a static file.
A file is a data store, just like a database. There is nothing wrong with using that symbol in a dataflow diagram. And since the arrow goes in one direction only, it is static (aka read-only).