Does EK Use J class for Mileage Upgrades?
 

A few days ago, my aunt used EK miles to upgrade her K class ticket to business class. Since it was a paper ticket, I saw a new sticker applied to the ticket. It said:

EK7 J OK.

AFAIK, J is the most expensive business class bucket that EK has. Is it possible / likely that they use J class for upgrades (and maybe even awards?) Or did the issuing agent just write J class to show that she was in business class?

Cheers