What type of code indicates restrictions placed on licenses?

The letter code is used to indicate restrictions that may be placed on a driver's license. Each letter corresponds to a specific restriction, such as requiring corrective lenses, having limitations on driving at night, or being allowed to drive only with an adult supervising. This system helps ensure that both law enforcement and the drivers themselves are aware of any limitations or conditions tied to their ability to operate a vehicle safely.

The other types of codes, such as numeric, symbol, and color codes, serve different purposes and do not specifically convey the same information regarding restrictions on a license. Numeric codes might be used for identification or categorization but lack the specific meaning that letter codes provide regarding operational limitations. Similarly, symbol codes may indicate general information about a driver's status or vehicle type, while color codes can represent various classifications or categories unrelated to restrictions.