Enumerators allow only reading the data in the collection. Enumerators cannot be used to modify the underlying collection.

Initially, the enumerator is positioned before the first element in the collection. The KeyContainerPermissionAccessEntryEnumerator.Reset method also brings the enumerator back to this position. At this position, calling the KeyContainerPermissionAccessEntryEnumerator.Current property throws an exception. Therefore, you must call the KeyContainerPermissionAccessEntryEnumerator.MoveNext method to advance the enumerator to the first element of the collection before reading the value of the KeyContainerPermissionAccessEntryEnumerator.Current property.

KeyContainerPermissionAccessEntryEnumerator.Current returns the same object until either KeyContainerPermissionAccessEntryEnumerator.MoveNext or KeyContainerPermissionAccessEntryEnumerator.Reset is called. KeyContainerPermissionAccessEntryEnumerator.MoveNext sets KeyContainerPermissionAccessEntryEnumerator.Current to the next element.

After the end of the collection is passed, the enumerator is positioned after the last element in the collection, and calling KeyContainerPermissionAccessEntryEnumerator.MoveNext returns false. If the last call to KeyContainerPermissionAccessEntryEnumerator.MoveNext returned false, calling KeyContainerPermissionAccessEntryEnumerator.Current throws an exception. To reset KeyContainerPermissionAccessEntryEnumerator.Current to the first element of the collection, call KeyContainerPermissionAccessEntryEnumerator.Reset followed by a call to KeyContainerPermissionAccessEntryEnumerator.MoveNext.

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and the next call to KeyContainerPermissionAccessEntryEnumerator.MoveNext or KeyContainerPermissionAccessEntryEnumerator.Reset throws an InvalidOperationException. If the collection is modified between calling KeyContainerPermissionAccessEntryEnumerator.MoveNext and KeyContainerPermissionAccessEntryEnumerator.Current, KeyContainerPermissionAccessEntryEnumerator.Current returns the element to which it is currently set, even if the enumerator is already invalidated.

The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.