Definition from IAI: This enumeration type is used to distinguish
between possible action types at a high level. It can be used for an automated
definition of load combinations and for dimensioning. The contained items and
their acronyms are adapted from the Eurocode standard.
The IfcActionTypeEnum type is referenced by the entity
IfcStructuralLoadGroup which shall normally be of the type
LOAD_COMBINATION_GROUP (see also IfcLoadGroupTypeEnum). If an
enumeration item is missing for an appropriate definition of a load group, the
item USERDEFINED shall be used instead. In this case, a meaning can be given by
using the IfcActionSourceTypeEnum.
HISTORY: New type in Release IFC2x
Edition 2.
