Steinberg? C7 project in C6.5

By accident I found out that C7.01 projects open in C6.5.4. Is this an intended feature? Can I depend on that working reliably? I understand that there are limitations to what 6.5 can open (for example no channel strip).

oh, BTW - can we open C7 projects in C5.5 ?
(sorry, I´m not at my studio)

YES. Have a look to 6.5 mixer. What you see ?

Would be nice to have an official reply. I would use C7 now if I knew I could go back if issues arise.