Of course a file can be open, or not open.
However, a file descriptor by definition refers to an open file (right?). (Well, except when it refers to something besides a file, like a pipe or what have you. But it's still open.)
I've encountered the phrase "open file descriptor" several times. I believe this is redundant, and that in fact there is no other kind of file descriptor besides an open file descriptor—but I would like to verify this.
Is a file descriptor ever in any other state besides "open"? (When it's closed, doesn't it cease to exist?)