I think the OP must be referring to UDU for EXP and is using a UA term. OP see:
http://www.flyertalk.com/forum/ameri...questions.html
From the wiki:
Expert Flyer (EF) will show you availability in class "A", which is used for SWUs and Miles+co-pay upgrades; you cannot see availability in EF for "sticker" upgrades.
You can also search for expertflyer in that thread: