So... "who knows what that spells?" As I see it there are 5 problems:
1) Are we supposed to be looking at a schematic map of Brooklyn's subway lines, or a geographically correct one?
2) Are we supposed to confine ourselves to Brooklyn while we traverse these lines (e.g., not take the G out to Queens)?
3) Are we supposed to start at the beginning or end of the L or somewhere in the middle?
4) Do we stop when we get to G or follow G to its end (or beginning)?
5) Is the trace of these line steps supposed to spell a letter or a word, or is there some clue at each transfer station to be found (station name, street name, landmark, etc.)?
My initial votes for answers to the above questions are 1) Geographic, 2) Yes (when possible), 3) The end of L (in Brooklyn), 4) Stop at G, and 5) a single letter.
I don't live in Brooklyn, nor am I inclined to travel there to unlock the song. But here is a good geographic subway map. Starting at the end of L (Canarsie-Rockaway Parkway), we get to J at Broadway Junction, then travel to F just inside lower Manhattan at Essex Street, and from there go to G at Bergen Street back in Brooklyn.
Tracing this on the geographic map yields nothing meaningful whatsoever.
I therefore assume that some of my assumptions are not assumable. Now I'm off to dig in Bob Dylan's garbage can. --Nehushtan 22:13, 6 Apr 2006 (CDT)