Are you referring to the e-certificates given to Charimans?

To/From Hawaii Advance Request Schedule

Y and H - Immediately after purchase – complimentary
All other economy fares 7 days* - upgrade credit required

To/From Europe Advance Request Schedule

Y and B - Anytime in advance* – upgrade credit required

M, H and Q - 7 days* - upgrade credit required
http://www.usair.com/awa/content/div...yupgrades.aspx