The name of the class is taken from the letter designating the first projected unit.

Each registration number begins with a letter designating type of vehicle.

The first letter designates the destination, the second indicates whether the train will call at every station or not.

The following letter designates polarity and general application of the device.

The additional letters designating traction type can also occur in combination.

Only three places in the United States use letters to designate a residence where a vehicle was registered.

A pair of letters designating a single phoneme is called a digraph.

First is the total number of boosters, then letters designating liquid- or solid-fueled stages.

The two letters together designate a processor class, while the number represents a PR rating.

The name "CMS-2" is followed in literature by a letter designating the type of target system.