A BIM.Feature is generic term referring to anything that belongs on or within a building surface. They are basically an abstract placeholder for accurately positioning and sizing things relative to a surface or BIM.Junction. Features can be used to position lights, sensors, switches, outlets, artwork, mounted HVAC equipment or controls panels, as well as apertures such as windows and doors.

A BIM.Aperture is a special type of feature that punctures entirely through a surface, providing an opening of some sort.