1 files changed, 3 insertions, 0 deletions
diff --git a/README.md b/README.md
index 631d590..ad1aea6 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,9 @@ Over apply:
 
 If no argument is passed, default to "printf %s\n".
 
+The current iteration is passed as `$ITER` to the child process
+(increased on every exec()).
+
 ## Return code
 
 Like GNU and OpenBSD xargs: