Default value
The y coordinate of the object on the map.
You may assign the coordinates of movable objects (mobs and objs), but this is not advisable. It is better to compute the new location (with locate()) and move them to that. Then you can use the normal Move() procedure, which enables all the normal movement behavior.
For areas that are on the map, this is the coordinate of the turf with the lowest z, y, and x coordinate (in that order) that is contained by the area.