Add
schema elements to a model by inserting them into the appropriate
collection.
Elements are removed
from the model by using either of the following methods:
Call the FdoSchemaElement::Delete() method.
This flags the element for deletion when the changes are accepted
(generally through FdoIApplySchema), but the element remains a member
of all collections until that time.
Remove the element from the appropriate collection
via the FdoSchemaCollection::Remove() or FdoSchemaCollection::RemoveAt() methods.
This immediately disassociates the element from the collection.