Replace `iff' in comments.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/systty.h b/src/systty.h
index 15dd7a4e26..c89edfc8d9 100644
--- a/src/systty.h
+++ b/src/systty.h
@@ -297,7 +297,7 @@ static struct sensemode {
    written before making the change.
    Return 0 if all went well, and -1 if anything failed.
 
-   EMACS_TTY_TABS_OK (struct emacs_tty *P) is false iff the kernel
+   EMACS_TTY_TABS_OK (struct emacs_tty *P) is false if the kernel
    expands tabs to spaces upon output; in that case, there is no
    advantage to using tabs over spaces.  */