Final answer:
The holder of a validated GDL (Graduated Driver's License) permit who is over 21 years old is restricted to both daytime and nighttime hours.
Step-by-step explanation:
The holder of a validated GDL (Graduated Driver's License) permit who is over 21 years old is restricted to both daytime and nighttime hours. This means that they can drive during the day as well as at night, but there may be specific restrictions on driving during certain nighttime hours, such as a curfew.