Welcome to FlyerTalk !

As a starter for you...

241 - Amex (or other credit card issuer) voucher that gives you a second redemption flight 'for free' - you just pay the fuel surcharges and taxes on each ticket.

UD - Upper Deck of the 747; widely considered the holy grail of Club World travel.

Y, W, J, F - the four classes of travel, in ascending order. Economy, Economy+, Business Class, First Class.

GUF2 - Gold Upgrade For 2. A voucher issued to Gold Card holders on reaching certain Tier Point thresholds. Does what it says on the tin - upgrades 2 travellers to the next class of travel.

GGL - Gold Guest List. The next step up from Gold Card. Brings extra privileges and rewards.

GCH - Gold Card Holder.

SCH - Silver Card Holder.

I'm sure more will be along soon...

BAH