Restricted Data (RD) is defined in the Atomic Energy Act of 1954 and covers nuclear weapons and related materials.

"[2] In addition to classification levels, three categories of classified matter are identified: Restricted Data (RD), Formerly Restricted Data (FRD), and National Security Information (NSI), as well as a class of access-restricted materials: special nuclear material (SNM).

The DOE security clearance process is overseen by the Department of Energy Office of Hearings and Appeals.

[citation needed] In Robert Heinlein's 1956 novel The Door Into Summer, the narrator says his pre-1960 Q clearance let him "soak up" much classified technology.

In the 2022 movie Moonfall Jocinda Fowler, played by actress Halle Berry, is given Q clearance by the director of NASA (Albert Hutchings) who gives her his ID access badge once he determines that collision with the Moon is imminent.