Is sub-domain considered cross-domain?

Question

Is http://nonsecure.form.xyz.org and https://secure.form.xyz.org considered different domain? I am asking this because my javascript in secure one cannot call it's parent. Secure domain is inside non-secure domain through an iframe.

EDIT

Conclusion

You can perform cross-domain scripting but cannot perform cross-protocol scripting (eg https and http)

Answer 1

What you can do here is set document.domain = "form.xyz.org" on both sides before attempting any cross-domain scripting.

However, you cannot cross-script between different protocols.