Art - Code on the Subway?

I've seen this poster on the subway lately and I like it (I took the image itself from the MTA's website).

I didn't notice it the first time I saw it, but what's with the letters and numbers on the bottom?

They're presented as the symbols for the various subway lines, including the colour the subway system uses on trains, signs and maps for each line, but there's no obvious order and the strings are different lengths.  Several are duplicated, but not all of them...  All of the subway lines are represented.

I suspect it's an encrypted message...

The symbols are:
LZN ABG3S FRJME76D R41CBS 5MQL2

Any ideas?  I've tried a few simple, basic decryption attempts, but no luck so far...

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Follow up on March 4, 2011

I wrote to the artist, Takayo Noda to ask if I was on the right track...  This is her reply:

Thank you for your Question / Comment.
I wish I had an exciting code to give you but the line numbers and letters are placed for the visual purpose. However, I was careful with not spell out any words with the letters.