Government officials were reminded recently that as they depart from government service with the end of the current Administration, they are not permitted to take classified information with them.

“Classified information is not personal property and may not be removed from the Government’s control by any departing official or employee. This includes ‘extra’copies.”

That timely warning (pdf) was issued by William J. Bosanko, the director of the Information Security Oversight Office, which oversees the national security classification system.

“This prohibition applies to all cleared officials and employees, regardless of type or level of position,” Mr. Bosanko wrote in a November 17 ISOO memorandum to senior executive branch agency officials.

Document removal is among the most pernicious forms of secrecy, as it is often undetected and irreversible.