AtomicConsistentIsolatedDurable without the "durable" part.  A model in which a database provides full serializable transaction semantics, but without guaranteeing that the system remains in a consistent state across a failure such as an unplanned reboot.  Better known as ACI.

Is this useful?  Certainly.  Some datasets are transient in nature--a database is used in processing some information, but the information can be regenerated from source (in a CAD tool for example).  Or, the data may be of limited value; such that data loss due to shutdown is more tolerable than the expense needed for full ACID semantics.

In effect, if the user requires Durability from all of his transactions, he is charged with providing it manually (performing saves, backups, etc. himself)