Definition from IAI:
Enumeration identifying the type of change that might have occurred
to the object during the last session (e.g., unchanged, added,
deleted, etc.). This information is required in a partial model
exchange scenario so that an application or model server will know
how an object might have been affected by the previous application.
Valid enumerations are:
- NOCHANGE: Object has not been modified. This is the
default state.
- MODIFIED: A modification to the object has been made
by the user and application defined by the
LastModifyingUser and LastModifyingApplication
respectively.
- ADDED: The object has been added by the user and
application defined by the LastModifyingUser
and LastModifyingApplication respectively.
- DELETED: The object has been deleted by the user and
application defined by the LastModifyingUser
and LastModifyingApplication respectively.
- MODIFIEDADDED: The object has been added and modified
by the user and application defined by the
LastModifyingUser and LastModifyingApplication
respectively.
- MODIFIEDDELETED: The object has been modified and deleted
by the user and application defined by the
LastModifyingUser and LastModifyingApplication
respectively.
Consider Application A receives an IFC dataset, adds a new object
and sets IfcChangeActionEnum to ADDED. Application B then receives
this IFC dataset but doesn't do anything to the object added by
Application A. Consequently, the object's IfcChangeActionEnum
remains set at ADDED. Consequently, the intent is that an
application only modifies the value of IfcChangeActionEnum when
it does something to the object, with the further intent that a
model server is responsible for clearing the IfcChangeActionEnum
back to UNCHANGED when it is checked back into the repository.
HISTORY: New enumeration in IFC R2.0.
ISSUES: See issues and change log for changes made in IFC R2x.
