IoT Message Store API lets you add up to ten custom headers to the objects you store for troubleshooting, informational purposes, or implementing particular logic on the client's or device's side.

You can create your custom headers by following the X-AK-Meta-* pattern. Your headers can be up to 128 characters long, and their values can be up to 64 characters long.

For instance, you can use the X-AK-Meta-Permission header to allow only a specific group of users to access your objects, or create a custom header to control device behavior after downloading a file.