When a player enters an unexplored dungeon of which he/she has no map data, the skill mapping will slowly and surely start creating a virtual map of the area as the player progresses through the dungeon.
Once the dungeon has been fully explored the players can then sell or give away their mapped data.
How it works
Mapping will level up every time you successfully map out a dungeon,and if a player leaves a dungeon mid-way he/she will lose all of the current data for that dungeon.
Once the dungeon has been fully mapped out the player will receive a chunk of experience depending on the dungeon difficulty and size. Bigger and harder dungeons will provide more experience, but will require a higher level to map out.