Classified information is material that a government body deems to be
sensitive information that must be protected. Access is restricted by
law or regulation to particular groups of people with the necessary
security clearance and need to know, and mishandling of the material
can incur criminal penalties. A formal security clearance is required
to view or handle classified documents or to access classified data.
The clearance process requires a satisfactory background
investigation. Documents and other information are marked with one of
several (hierarchical) levels of sensitivity—e.g. restricted,
confidential, secret and top secret. The choice of level is based on
an impact assessment; governments have their own criteria, which
include how to determine the classification of an information asset,
and rules on how to protect information classified at each level. This
often includes security clearances for personnel handling the
information. Although "classified information" refers to the formal
categorization and marking of material by level of sensitivity, it has
also developed a sense synonymous with "censored" in US English. A
distinction is often made between formal security classification and
privacy markings such as "commercial in confidence". Classifications
can be used with additional keywords that give more detailed
instructions on how data should be used or protected.
Some corporations and non-government organizations also assign
sensitive information to multiple levels of protection, either from a
desire to protect trade secrets, or because of laws and regulations
governing various matters such as personal privacy, sealed legal
proceedings and the timing of financial information releases.
With the passage of time much classified information becomes much less
sensitive, and may be declassified and made public. Since the late
twentieth century there has been freedom of information legislation in
some countries, whereby the public is deemed to have the right to all
information that is not considered to be damaging if released.
Sometimes documents are released with information still considered
confidential obscured (redacted), as in the example at right.
1 Government classification
2 Typical classification levels
2.1 Top Secret (TS)
2.8 Compartmented information
3.2 International organisations
4 By country
4.3.1 Background and hierarchy
Special operational information
4.3.3 Classified information
4.3.4 Protected information
4.4 People's Republic of China
4.6 Hong Kong
4.7 New Zealand
4.11 United Kingdom
4.12 United States
4.13 Table of equivalent classification markings in various countries
5 Corporate classification
6 Traffic Light Protocol
7 See also
9 External links
The purpose of classification is to protect information. Higher
classifications protect information that might endanger national
security. Classification formalises what constitutes a "state secret"
and accords different levels of protection based on the expected
damage the information might cause in the wrong hands.
However, classified information is frequently "leaked" to reporters by
officials for political purposes. Several U.S. presidents have leaked
sensitive information to get their point across to the public.
Typical classification levels
Although the classification systems vary from country to country, most
have levels corresponding to the following British definitions (from
the highest level to lowest).
Top Secret (TS)
KGB traitors list seen in Museum of Genocide Victims Vilnius:
originally marked top secret
Top Secret is the highest level of classified information.
Information is further compartmented so that specific access using a
code word after top secret is a legal way to hide collective and
important information. Such material would cause "exceptionally
grave damage" to national security if made publicly available.
Prior to 1942, the
United Kingdom and other members of the British
Empire used Most Secret, but this was later changed to match the
United States' category name of Top Secret in order to simplify Allied
The Washington Post
The Washington Post reports in an investigation entitled Top Secret
America, that per 2010 "An estimated 854,000 people ... hold
top-secret security clearances" in the United States.
“It is desired that no document be released which refers to
experiments with humans and might have adverse effect on public
opinion or result in legal suits. Documents covering such work field
should be classified 'secret'.”
April 17, 1947 Atomic Energy Commission memo from Colonel O.G.
Haywood, Jr. to Dr. Fidler at the Oak Ridge Laboratory in
Tennessee. As of 2010,
Executive Order 13526
Executive Order 13526 bans classification of
documents simply to "conceal violations of law, inefficiency, or
administrative error" or "prevent embarrassment to a person,
organization, or agency".
Secret material would cause "serious damage" to national security if
it were publicly available.
In the United States, operational "Secret" information can be marked
with an additional "LIMDIS", to limit distribution.
Confidential material would cause damage or be prejudicial to national
security if publicly available.
Restricted material would cause "undesirable effects" if publicly
available. Some countries do not have such a classification; in public
sectors, such as commercial industries. Such a level is also known as
Official (Equivalent to US DOD classification FOUO – For Official
Use Only) material forms the generality of government business, public
service delivery and commercial activity. This includes a diverse
range of information, of varying sensitivities, and with differing
consequences resulting from compromise or loss. OFFICIAL information
must be secured against a threat model that is broadly similar to that
faced by a large private company.
The OFFICIAL classification replaced the Confidential and Restricted
classifications in April 2014 in the UK.
Unclassified is technically not a classification level, but this is a
feature of some classification schemes, used for government documents
that do not merit a particular classification or which have been
declassified. This is because the information is low-impact, and
therefore does not require any special protection, such as vetting of
A plethora of pseudo-classifications exist under this category.
Clearance is a general classification, that comprises a variety of
rules controlling the level of permission required to view some
classified information, and how it must be stored, transmitted, and
destroyed. Additionally, access is restricted on a "need to know"
basis. Simply possessing a clearance does not automatically authorize
the individual to view all material classified at that level or below
that level. The individual must present a legitimate "need to know" in
addition to the proper level of clearance.
In addition to the general risk-based classification levels,
additional compartmented constraints on access exist, such as (in the
Special Intelligence (SI), which protects intelligence sources
and methods, No Foreign dissemination (NOFORN), which restricts
dissemination to U.S. nationals, and Originator Controlled
dissemination (ORCON), which ensures that the originator can track
possessors of the information. Information in these compartments is
usually marked with specific keywords in addition to the
Government information about nuclear weapons often has an additional
marking to show it contains such information (CNWDI).
When a government agency or group shares information between an agency
or group of other country’s government they will generally employ a
special classification scheme that both parties have previously agreed
For example, the marking ATOMAL, is applied to U.S. RESTRICTED DATA or
FORMERLY RESTRICTED DATA and
United Kingdom ATOMIC information that
has been released to NATO. ATOMAL information is marked COSMIC TOP
SECRET ATOMAL (CTSA),
NATO SECRET ATOMAL (NSAT), or
For example, sensitive information shared amongst
NATO allies has four
levels of security classification; from most to least classified:
COSMIC TOP SECRET (CTS)
NATO SECRET (NS)
NATO CONFIDENTIAL (NC)
NATO RESTRICTED (NR)
A special case exists with regard to
NATO UNCLASSIFIED (NU)
information. Documents with this marking are
NATO property (copyright)
and must not be made public without
European Commission, has five levels: EU TOP SECRET, EU SECRET, EU
CONFIDENTIAL, EU RESTRICTED, and EU COUNCIL / COMMISSION. (Note
that usually the French term is used.)
TRÈS SECRET UE/EU TOP SECRET: information and material the
unauthorised disclosure of which could cause exceptionally grave
prejudice to the essential interests of the
European Union or of one
or more of the Member States;
SECRET UE/EU SECRET: information and material the unauthorised
disclosure of which could seriously harm the essential interests of
European Union or of one or more of the Member States;
CONFIDENTIEL UE/EU CONFIDENTIAL: information and material the
unauthorised disclosure of which could harm the essential interests of
European Union or of one or more of the Member States;
RESTREINT UE/EU RESTRICTED: information and material the unauthorised
disclosure of which could be disadvantageous to the interests of the
European Union or of one or more of the Member States.
Organisation for Joint Armament Cooperation, a European defence
organisation, has three levels of classification: OCCAR SECRET, OCCAR
CONFIDENTIAL, and OCCAR RESTRICTED.
ECIPS, the European Centre for Information Policy and Security, has 4
levels of Security Information, COSMIC (TOP SECRET), EC-SECRET,
EC-CONFIDENTIAL and EC-COMMITTEES.
Facsimile of the cover page from an East German operation manual for
Fialka cipher machine. The underlined classification
markings can be translated as "Cryptologic material! Secret restricted
Most countries employ some sort of classification system for certain
government information. For example, in Canada, information that the
U.S. would classify SBU (Sensitive but Unclassified) is called
"protected" and further subcategorised into levels A, B, and C.
On 19 July 2011, the National Security (NS) classification marking
scheme and the Non-National Security (NNS) classification marking
Australia was unified into one structure.
The Australian Government Security Classification system now comprises
TOP SECRET, SECRET, CONFIDENTIAL and PROTECTED. A new dissemination
limiting markers (DLMs) scheme was also introduced for information
where disclosure may be limited or prohibited by legislation, or where
it may otherwise require special handling. The DLM marking scheme
For Official Use Only (FOUO), Sensitive, Sensitive:
Personal, Sensitive: Legal, and Sensitive: Cabinet.
Documents marked Sensitive Cabinet, relating to discussions in Federal
Cabinet, are treated as PROTECTED at minimum due to its higher
There are three levels of document classification under Brazilian
Information Access Law: ultrassecreto (top secret), secreto (secret)
and reservado (restricted).
A top secret (ultrassecreto) government-issued document may be
classified for a period of 25 years, which may be extended up to
another 25 years. Thus, no document remains classified for more than
50 years. This is mandated by the 2011 Information Access
Law (Lei de
Acesso à Informação), a change from the previous rule, under which
documents could have their classification time length renewed
indefinitely, effectively shuttering state secrets from the public.
The 2011 law applies retroactively to existing documents.
Further information: Security Clearances in Canada
Background and hierarchy
The Government of
Canada employs two main types of sensitive
information designation: Classified and Protected. The access and
protection of both types of information is governed by the Security of
Information Act, effective December 24, 2001, replacing the Official
Secrets Act 1981. To access the information, a person must have
the appropriate security clearance and the need to know.
In addition, the caveat "Canadian Eyes Only" is used to restrict
access to Classified or Protected information only to Canadian
citizens with the appropriate security clearance and need to know.
Special operational information
SOI is not a classification of data per se. It is defined under the
Security of Information Act, and unauthorised release of such
information constitutes a higher breach of trust, with penalty of life
military operations in respect of a potential, imminent or present
the identity of confidential source of information, intelligence or
assistance to the Government of Canada
tools used for information gathering or intelligence
the object of a covert investigation, or a covert collection of
information or intelligence
the identity of any person who is under covert surveillance
encryption and cryptographic systems
information or intelligence to, or received from, a foreign entity or
Classified information can be designated Top Secret, Secret or
Confidential. These classifications are only used on matters of
Top Secret: applies when compromise might reasonably cause
exceptionally grave injury to the national interest. The possible
impact must be great, immediate and irreparable.
Secret: applies when compromise might reasonably cause serious injury
to the national interest.
Confidential: disclosure might reasonably cause injury to the national
Protected information is not classified. It pertains to any sensitive
information that does not relate to national security and cannot be
disclosed under the access and privacy legislation because of the
potential injury to particular public or private interests.
Protected C (Extremely Sensitive protected information): designates
extremely sensitive information, which if compromised, could
reasonably be expected to cause extremely grave injury outside the
national interest. Examples include bankruptcy, identities of
informants in criminal investigations, etc.
Protected B (Particularly Sensitive protected information): designates
information that could cause severe injury or damage to the people or
group involved if it was released. Examples include medical records,
annual personnel performance reviews, income tax returns, etc.
Protected A (Low-Sensitive protected information): designates low
sensitivity information that should not be disclosed to the public
without authorization and could reasonably be expected to cause injury
or embarrassment outside the national interest. Example of Protected A
information include employee identification number, pay deposit
banking information, etc.
Federal Cabinet (Queen's Privy Council for Canada) papers are either
protected (e.g., overhead slides prepared to make presentations to
Cabinet) or classified (e.g., draft legislation, certain memos).
People's Republic of China
A building in
Wuhan housing provincial offices for dealing with
foreign countries etc. The red slogan says, "Protection of national
secrets is a duty of every citizen".
Law of the
People's Republic of China
People's Republic of China (which is not
operative in the
Special Administrative Regions of
Hong Kong and
Macao) makes it a crime to release a state secret. Regulation and
enforcement is carried out by the National Administration for the
Protection of State Secrets.
Under the 1989 "
Law on Guarding State Secrets," state secrets are
defined as those that concern:
Major policy decisions on state affairs
The building of national defence and in the activities of the armed
Diplomatic activities and in activities related to foreign countries
and those to be maintained as commitments to foreign countries
National economic and social development
Science and technology
Activities for preserving state security and the investigation of
Any other matters classified as "state secrets" by the national State
Secrets can be classified into three categories:
Top secret (绝密): defined as "vital state secrets whose disclosure
would cause extremely serious harm to state security and national
Highly secret (机密): defined as "important state secrets whose
disclosure would cause serious harm to state security and national
Secret (秘密): defined as "ordinary state secrets whose disclosure
would cause harm to state security and national interests"
In France, classified information is defined by article 413-9 of the
Penal Code. The three levels of military classification are
Très Secret Défense (Very Secret Defence): Information deemed
extremely harmful to national defense, and relative
to governmental priorities in national defense. No service or
organisation can elaborate, process, stock, transfer, display or
destroy information or protected supports classified at this level
without authorization from the Prime Minister or the national
secretary for National Defence. Partial or exhaustive reproduction is
Secret Défense (Secret Defence): Information deemed very harmful to
national defense. Such information cannot be reproduced without
authorisation from the emitting authority, except in exceptional
Confidentiel Défense (Confidential Defence): Information deemed
potentially harmful to national defense, or that could lead to
uncovering some information classified at a higher level of security.
Less sensitive information is "protected". The levels are
Confidentiel personnels Officiers ("Confidential officers")
Confidentiel personnels Sous-Officiers ("Confidential non-commissioned
Diffusion restreinte ("restricted information")
Diffusion restreinte administrateur ("administrative restricted
Non Protégé (unprotected)
A further caveat, "spécial France" (reserved France) restricts the
document to French citizens (in its entirety or by extracts). This is
not a classification level.
Declassification of documents can be done by the Commission
consultative du secret de la défense nationale (CCSDN), an
independent authority. Transfer of classified information is done with
double envelopes, the outer layer being plastified and numbered, and
the inner in strong paper. Reception of the document involves
examination of the physical integrity of the container and
registration of the document. In foreign countries, the document must
be transferred through specialised military mail or diplomatic bag.
Transport is done by an authorised convoyer or habilitated person for
mail under 20 kg. The letter must bear a seal mentioning "PAR
VALISE ACCOMPAGNEE-SACOCHE". Once a year, ministers have an inventory
of classified information and supports by competent authorities.
Once their usage period is expired, documents are transferred to
archives, where they are either destroyed (by incineration, crushing,
or overvoltage), or stored.
In case of unauthorized release of classified information, competent
authorities are the Ministry of Interior, the Haut fonctionnaire de
défense et de sécurité ("high civil servant for defence and
security") of the relevant ministry, and the General secretary for
National Defence. Violation of such secrets is an offence punishable
with 7 years of imprisonment and a 100,000 Euro fine; if the offence
is committed by imprudence or negligence, the penalties are 3 years of
imprisonment and a 45,000 Euro fine.
The Security Bureau is responsible for developing policies in regards
to the protection and handling of confidential government information.
In general, the system used in
Hong Kong is very similar to the UK
system, developed from the
Colonial Hong Kong
Colonial Hong Kong era.
Four classifications exists in Hong Kong, from highest to lowest in
Top Secret (絕對機密)
Temporary Confidential (臨時保密)
Restricted (staff) (限閱文件(人事))
Restricted (tender) (限閱文件 (投標))
Restricted (administration) (限閱文件 (行政))
Restricted documents are not classified per se, but only those who
have a need to know will have access to such information, in
accordance with the Personal Data (Privacy) Ordinance.
New Zealand uses the Restricted classification, which is lower than
Confidential. People may be given access to Restricted information on
the strength of an authorisation by their Head of Department, without
being subjected to the background vetting associated with
Confidential, Secret and Top Secret clearances. New Zealand's security
classifications and the national-harm requirements associated with
their use are roughly similar to those of the United States.
In addition to national security classifications there are two
additional security classifications, In Confidence and Sensitive,
which are used to protect information of a policy and privacy nature.
There are also a number of information markings used within ministries
and departments of the government, to indicate, for example, that
information should not be released outside the originating ministry.
Because of strict privacy requirements around personal information,
personnel files are controlled in all parts of the public and private
sectors. Information relating to the security vetting of an individual
is usually classified at the In Confidence level.
In Romania, classified information is referred to as "state secrets"
(secrete de stat) and is defined by the Penal Code as "documents and
data that manifestly appear to have this status or have been declared
or qualified as such by decision of Government". There are three
levels of classification—Secret, Top Secret, and Top Secret of
Particular Importance. The levels are set by the Romanian
Intelligence Service and must be aligned with
case of conflicting regulations, the latter are applied with priority.
Dissemination of classified information to foreign agents or powers is
punishable by up to life imprisonment, if such dissemination threatens
Romania's national security.
KGB Regulation seen in Museum of Genocide Victims Vilnius
Classified information in Russia
In the Russian Federation, a state secret
(Государственная тайна) is information protected
by the state on its military, foreign policy, economic, intelligence,
counterintelligence, operational and investigative and other
activities, dissemination of which could harm state security.
Some Swedish examples of markings attached to documents that are to be
kept secret. A single frame around the text indicates Hemlig, which
can be equal to either Secret, Confidential or Restricted. Double
frames means Kvalificerat hemlig, that is, Top Secret.
The Swedish classification has been updated due to increased NATO/PfP
cooperation. All classified defence documents will now have both a
Swedish classification (Kvalificerat hemlig or Hemlig), and an English
classification (Top Secret, Secret, Confidential, or
Restricted). The term skyddad identitet, "protected
identity", is used in the case of protection of a threatened person,
basically implying "secret identity", accessible only to certain
members of the police force and explicitly authorised officials.
Security classifications in the UK
Classified information in the United Kingdom
Until 2013, the
United Kingdom used five levels of
classification—from lowest to highest, they were: PROTECT,
RESTRICTED, CONFIDENTIAL, SECRET and TOP SECRET (formerly MOST
Cabinet Office provides guidance on how to protect
information, including the security clearances required for personnel.
Staff may be required to sign to confirm their understanding and
acceptance of the Official Secrets Acts 1911 to 1989, although the Act
applies regardless of signature. PROTECT is not in itself a security
protective marking level (such as RESTRICTED or greater), but is used
to indicate information which should not be disclosed because, for
instance, the document contains tax, national insurance, or other
Government documents without a classification may be marked as
UNCLASSIFIED or NOT PROTECTIVELY MARKED.
This system was replaced by the Government Security Classifications
Policy, which has a simpler model: TOP SECRET, SECRET, and OFFICIAL
from April 2014. OFFICIAL SENSITIVE is a security marking which
may be followed by one of three authorised descriptors: COMMERCIAL,
LOCSEN (location sensitive) or PERSONAL. SECRET and TOP SECRET may
include a caveat such as UK EYES ONLY.
Classified information in the United States
The U.S. classification system is currently established under
Executive Order 13526
Executive Order 13526 and has three levels of
classification—Confidential, Secret, and Top Secret. The U.S. had a
Restricted level during
World War II
World War II but no longer does. U.S.
regulations state that information received from other countries at
the Restricted level should be handled as Confidential. A variety of
markings are used for material that is not classified, but whose
distribution is limited administratively or by other laws, e.g., For
Official Use Only (FOUO), or
Sensitive but Unclassified
Sensitive but Unclassified (SBU). The
Atomic Energy Act of 1954 provides for the protection of information
related to the design of nuclear weapons. The term "Restricted Data"
is used to denote certain nuclear technology. Information about the
storage, use or handling of nuclear material or weapons is marked
"Formerly Restricted Data". These designations are used in addition to
level markings (Confidential, Secret and Top Secret). Information
protected by the Atomic Energy Act is protected by law and information
classified under the Executive Order is protected by Executive
The U.S. government insists it is "not appropriate" for a court to
question whether any document is legally classified. In the 1973
Daniel Ellsberg for releasing the Pentagon Papers, the judge
did not allow any testimony from Ellsberg, claiming it was
"irrelevant", because the assigned classification could not be
challenged. The charges against Ellsberg were ultimately dismissed
after it was revealed that the government had broken the law in
secretly breaking into the office of Ellsberg's psychiatrist and in
tapping his telephone without a warrant. Ellsberg insists that the
legal situation in the U.S. today is worse than it was in 1973, and
Edward Snowden could not get a fair trial. The State Secrets
Protection Act of 2008 might have given judges the authority to review
such questions in camera, but the bill was not passed.
Table of equivalent classification markings in various countries
Estrictamente Secreto y Confidencial
Zeer Geheim / Très Secret
Geheim / Secret
Vertrouwelijk / Confidentiel
Beperkte Verspreiding / Diffusion restreinte
or Muy Secreto
Bosnia and Herzegovina
no equivalent (formerly Confidencial)
За служебно ползване
Sam Ngat Bamphot
Sam Ngat Roeung
Ham Kom Psay
Top Secret/Très secret
Protected A, B or C / Protégé A, B ou C
China, People's Republic of
Reserva del sumario
(thin Black border)
Yemiaz Birtou Mistir
European Union (EU)
TRES SECRET UE / EU TOP SECRET
SECRET UE / EU SECRET
CONFIDENTIEL UE / EU CONFIDENTIAL
RESTREINT UE / EU RESTRICTED
European Union (Western) (WEU)
FOCAL TOP SECRET
EURA TOP SECRET
Erittäin salainen (ST I)
Salainen (ST II)
Luottamuksellinen (ST III)
Käyttö rajoitettu (ST IV)
Très secret défense
VS-Nur für den Dienstgebrauch
Top Secret, 高度機密
परम गुप्त (Param Gupt)
Bekoli-Serri بکلی سری
Kheili-Mahramaneh خیلی محرمانه
Ireland (Irish language)
I(Il)-geup Bimil, 1급비밀
II(I)-geup Bimil, 2급비밀
III(Sam)-geup Bimil, 3급비밀
Lup Sood Gnod
Chum Kut Kon Arn
STG. Zeer Geheim
Barai Mahdud Taqsim
Mahigpit na Lihim
Strict Secret de Importanță Deosebită
Secret de serviciu
(вариант: Совершенно Секретно (Sovershenno
(вариант: Секретно (Sekretno))
(вариант: Не подлежит оглашению
(Конфиденциально) (Ne podlezhit oglasheniyu
Для Служебного Пользования (ДСП)
(Dlya Sluzhebnogo Pol'zovaniya)
Saudi Top Secret
Saudi Very Secret
Latin: Državna tajna
Cyrillic: Државна тајна
Latin: Strogo poverljivo
Cyrillic: Строго поверљиво
Sir Muhiim ah
Kvalificerat Hemlig (KH); Hemlig/Top Secret (H/TS)
Hemlig (H); Hemlig/Secret H/S)
GEHEIM / SECRET
VERTRAULICH / CONFIDENTIEL
INTERN / INTERNE
Taiwan (Republic of China)
Top Secret (絕對機密)
no direct equivalent
Lap thi sut (ลับที่สุด)
Lap mak (ลับมาก)
Pok pit (ปกปิด)
South Africa (English)
South Africa (Afrikaans)
Для службового користування
OFFICIAL-SENSITIVE (formerly CONFIDENTIAL)
OFFICIAL (formerly RESTRICTED)
no direct equivalent
Phổ Biến Hạn Chế
NISPOM Appendix B ¹ In addition,
label Salassa pidettävä, "to be kept secret" for information that is
not classified but must not be revealed on some other basis than
national security. (E.g. privacy, trade secrets etc.)
Private corporations often require written confidentiality agreements
and conduct background checks on candidates for sensitive
positions. In the U.S. the Employee Polygraph Protection Act
prohibits private employers from requiring lie detector tests, but
there are a few exceptions. Policies dictating methods for marking and
safeguarding company-sensitive information (e.g. "IBM Confidential")
are common and some companies have more than one level. Such
information is protected under trade secret laws. New product
development teams are often sequestered and forbidden to share
information about their efforts with un-cleared fellow employees, the
Apple Macintosh project being a famous example. Other
activities, such as mergers and financial report preparation generally
involve similar restrictions. However, corporate security generally
lacks the elaborate hierarchical clearance and sensitivity structures
and the harsh criminal sanctions that give government classification
systems their particular tone.
Traffic Light Protocol
The Traffic Light Protocol was developed by the Group of Eight
countries to enable the sharing of sensitive information between
government agencies and corporations. This protocol has now been
accepted as a model for trusted information exchange by over 30 other
countries. The protocol provides for four "information sharing levels"
for the handling of sensitive information.
Economic Espionage Act of 1996
Economic Espionage Act of 1996 (U.S.)
Espionage Act of 1917 (U.S.)
Government Security Classifications Policy
Government Security Classifications Policy (UK)
Official Secrets Act
Official Secrets Act (UK, India, Ireland, Malaysia, New Zealand)
Security of Information Act (Canada)
State Secrets Privilege (US)
Golden Shield Project
United States Cryptologic History: Attack on a Sigint Collector,
the U.S.S. Liberty" (PDF). NSA.gov. Archived from the original (PDF)
on 2012-10-30. Retrieved 2012-11-14.
^ Turner, Stansfield (2005). Burn Before Reading: Presidents, CIA
Directors and Secret Intelligence. New York: Hyperion.
^ Goldsmith, Jack (29 September 2010). "Classified Information in
Woodward's 'Obama's Wars'". Lawfare. Retrieved 5 September 2015.
^ Random House Webster's Unabridged Dictionary (2. ed., [Nachdr.]
ed.). New York [u.a.]: Random House. 2004. ISBN 0375425993.
Defense Technical Information Center
Defense Technical Information Center (April 1997). "DoD Guide to
Marking Classified Documents" (PDF). dtic.mil.
Federation of American Scientists
Federation of American Scientists (June 8, 2013). "Chapter 7.
CLASSIFICATION LEVELS". fas.org.
^ Priest, Dana; Arkin, William (19 July 2010). "A hidden world,
growing beyond control". The Washington Post. Retrieved 5 September
^ Atomic Energy Commission's Declassification Review of Reports on
Human Experiments and the Public Relations and Legal Liability
Consequences, presented as evidence during the 1994 ACHRE hearings.
^ Section 1.7 (1) and (2).
United States Coast Guard. "E-PME Enlisted PROFESSIONAL MILITARY
EDUCATION Reporting Unsecured and Securing Classified Material 4.G.03"
(PDF). uscg.mil. [permanent dead link]
^ George Washington University. "ATTACHMENT 2 AR 320-5, CLASSIFICATION
OFC. Army Regulations (1936)". gwu.edu.
^ a b Government Security Classifications April 2014. HMG Cabinet
Office. October 2013.
^ "Decision of 23 September 2013 on the security rules for protecting
EU classified information". Official Journal of the European Union. 15
October 2013. Retrieved 5 September 2015.
^ "306652_CM6554" (PDF). Archived from the original (PDF) on
2005-05-25. Retrieved 2012-11-14.
Information security management guidelines (PDF),
Attorney-General’s Department, 18 July 2011, archived (PDF) from the
original on 4 May 2013
^ Security of Information Act, Archived January 16, 2008, at
^ "Industrial Security Services - Frequently Asked Questions". Public
Works and Government Services Canada. Government of Canada. Retrieved
8 November 2012. [permanent dead link]
^ "ARCHIVED - Non-Insured Health Benefits Program: Privacy Code, 2005
(Appendix II)". Health Canada, First Nations and Inuit Health Branch.
2015. Retrieved 5 September 2015.
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