This listing contains detailed descriptions of the file classification system for documents available from the Public Document Room (PDR) of the US Nuclear Regulatory Commission. As a public service branch of the agency, the PDR maintains facilities for receiving, processing, storing, and retrieving documents which NRC generates or receives in performing its regulatory function. Unlike a library, the PDR does not maintain collections of formally published materials, such as books, monographs, serials, periodicals, or general indexes. The documents on file at the PDR can be reports, written records of meetings (transcripts), existing or proposed regulations, the text of licenses or their amendments, and correspondence.