Maps are single files, that define bi-dimensional matrices of cells, each cell has the following attributes:
Height. From 0 to 20
Surface type. There are 5 surface types, and the map editor numbering system indicates the texture type, the texture file itself depends on the tileset.
Object. A cell can have an object or not, there are 10 types of objects, object models depend on the tileset, but in general terms, objects 1 and 2 are trees, 3 is stone, 4 and 5 are bushes, objects from 6 to 9 can be anything and 10 is an invisible blocking object.
Resource. Resources can be placed on cells. objects and resources cannot share the same cell at the same time. Resources depend on the Tech Tree.
Maps also define the start locations for each player, map size, altitude factor, and water level. Maps cannot define the placement of units or buildings. To play maps created with the editor, just place the .gbm file into the Glest directory map folder.