A window is a pane of glass enclosed in framework. One window may include multiple panes separated by thin strips of wood or metal. These strips form the dividers between panes within a larger frame. If the size of these strips exceeds 7.5 cm (3 in) the area becomes two separate windows. As well, if the distance between the windows is a solid part of the wall, not a part of the window frame, the area becomes two separate windows.
A single window must fit into one wall opening, in a single frame. To be considered a window, it must be an above-grade window, meaning the window is completely above ground level.
Also, the window width or height must be at least 30 cm (12 in). Windows smaller than this are not to be included.
An example of one window, the panes are separated by thin strips and fitting into one opening in the wall
An example of three windows, each pane is in its own individual frame
Below-grade basement windows are not included window classification