Wall and Window IDs in the LENICALC program and LENIXML files

 A room is simply a polygon. The first wall of the room is the line from the first coordinate in the polygon to the second coordinate in the polygon, and so on. The first wall has id "0",  the second wall id "1", and so on.

Windows belong to rooms, in fact windows belong to walls in a room. The window's id is formed by the wall id and the window id. The window id is simply an integer starting at "0" for the first window added to that wall. The second window added to the wall will have id "1", and so on. The window id does not define a geometrical order, only the historical order of when the window was added to the room.

Here is an example:

 

So the window XML says which wall it belongs to, as well as its height and width, and also how far along the wall it is. The x position of the window is measured from the start of the wall on the right when looking at the wall from inside the room:

The y position is the distance from the floor to the bottom of the window. 1 meter in the above example.