Definition from IAI: The element type (IfcElementType)
defines a list of commonly shared property set definitions of an element and an
optional set of product representations. It is used to define an element
specification (i.e. the specific product information, that is common to all
occurences of that product type).
NOTE: The product representations are defined as
representation maps (at the level of the supertype IfcTypeProduct, which
gets assigned by an element instance through the
IfcShapeRepresentation.Item[1] being an
IfcMappedItem.
An element type is used to define the common properties of a certain
type or style of an element that may be applied to instances of that element
type to assign a specific style. Element types (the instantiable subtypes) may
be exchanged without being already assigned to occurrences.
HISTORY New entity in Release IFC2x
Edition 2