Rooms for a text-based game (MUD-like)

Question

Hello,

As a project me and some friends have decided to build a MUD (Multi User Dungeon) like game, but we have encountered a little issue regarding the way we will have the coordinates set.

What would be the easiest way to define the coordinates of the player at any time - and allow him to move to different directions (up,down,left and right).

Keep in mind - this is a text based game without any graphical support.

Thank you in advance,
Sleepingcap