Thanks,

I obtained the I info (vs. U) from the below FAQ. Now that I look at it again, it's specifically for 'mid-tier', maybe that is the difference between I and U classes.

http://www.flyertalk.com/forum/catha...iles-faqs.html

Is there any requirement on the underlying booking sub-classes when using a mid-tier bookable upgrade?
Yes, the original flight needs to be booked in an “upgradable” sub-class, the same sub-classes that qualify for Asia Miles upgrades :
Economy: Fare classes [Y B H K M] will be upgraded into fare class E
Premium Economy: Fare classes [W R] will be upgraded into fare class I
Business: Fare classes [J C D I] will be upgraded into fare class A


Based on your response I can find upgrade award availability by checking for regular award redemption on the CX site. Thanks for confirming.

thanks,
RDP