About the map
While being trapped under one of the blast doors during the lockdown incident in the Swan station, Locke saw a huge, hand-drawn map on the surface of one of the blast doors. The map was allegedly created by DHARMA Initiative member Stuart Radzinsky and later worked on by Kelvin Inman. ("Lockdown")
Locke later tried to recreate the map on paper by drawing what he remembered. He only had a few seconds looking at the blast door map, so his memories of the details were rather patchy.
Locke drew onto his map the "?" at the center and the octagon shape, as these were the main things he was able to pull from memory. Locke also drew an arrow to indicate the the Arrow station at the top right. Locke himself never visited the Arrow station, although it is possible he knew the location and symbol of this station from the tail section survivors. Locke clearly drew a "3" to indicate the Swan station where he was located; he knew the Swan was station three from the Swan Orientation film. When he tried to draw the map in the episode "S.O.S.", Locke and Jack did not know (yet) about the medical station, so he didn't put it on his map. On his final mapping attempt, an arrow and an "S", or a drawing of a swan, appeared to be written. This shows that he was a bit more accurate on this attempt as he clearly remembered the "?" as well as the Swan station's and Arrow station's placement. Locke finally drew a good copy, which is seen in "?", when he handed it to Eko.
It is revealed in "?" that the question mark was the location of the Pearl station. While in the Pearl, Locke got rid of the map by sending it through the pneumatic tube. This map bore more resemblance to Locke's first attempt at transcription than his second, suggesting a third attempt, or that he returned to the initial map. The map reappeared in "Live Together, Die Alone". It was in the pile of tubes that were being sent from the Pearl's pneumatic tube system. Sawyer took the map and handed it to Jack.
The map was written over a copy of Alfred de Musset's poem Sur les Débuts de Mesdemoiselles Rachel et Pauline Garcia.