Presumably these allow WED to select the wall/fence type and associated objects for each section by name.
Also some façade files on distribution have the wrong file extension for the image file yet the façade file still works.
eg Classic_Garage_1.fac uses TEXTURE ../../textures/Classic_Airport.png whereas the file is ../../textures/Classic_Airport.dds
Does the façade engine force .dds and if so can this be made clear?