Just a wild guess, but here's a couple of bits from an interview with ASI. I don't know enough about paintwork to say whether the highlighted bits may relate to the letters you've identified, especially the second one:
Mark Gregory sifts through the mangled remains of a seven-year-old Boeing (BA) 737-700. Traces of orange on the tail betray the plane’s prior life as a
member of EasyJet’s (EZJ:LN) fleet. His gray ponytail bobbing in the wind of the Cotswolds countryside,
There’s no shortage of cadavers. Leasing companies pay Gregory approximately $50,000 per plane to tear apart their aircraft and separate the engines to re-lease or sell them and consign the remains to parts companies.
Much of the yard’s work last year involved Airbus (EAD:FP) A320s and Boeing 737 Classics.
EDIT I've discovered that those references are part of the stock market identifiers.

I should stick to what I know, which ain't much.