The older system used five levels of classification, supplemented with caveat keywords. The keyword was placed in all capital letters in the centre of the top and bottom of each page of a classified document and described the foreseeable consequence of an unauthorised release of the data (a ‘breach of confidentiality’). In descending order of secrecy, these are: ; TOP SECRET : Information marked as
TOP SECRET is that whose release is liable to cause considerable loss of life, international diplomatic incidents, or severely impact ongoing intelligence operations. Prior to the
Second World War, the highest level was "Most Secret"; it was renamed so that both the UK and U.S. operated to a consistent system. ; SECRET : This marking is used for information whose side-effects may be life-threatening, disruptive to public order or detrimental to diplomatic relations with friendly nations. ; CONFIDENTIAL : The effects of releasing information marked as
CONFIDENTIAL include considerable infringement on personal liberties, material damage to diplomatic relations, or to seriously disrupt day-to-day life in the country. ; RESTRICTED : Information marked as
RESTRICTED is at a level where the release of the material will have effects such as significant distress to individuals, adversely affecting the effectiveness of military operations, or to compromise law enforcement. ; PROTECT : Such information will cause distress to individuals; cause financial loss or improper gain; prejudice the investigation of, or facilitate the commission of, a crime; or disadvantage government in commercial or policy negotiations with others. PROTECT should always be used with a descript such as “Commercial”, “Management”, “Personal”, or a similar term. ; UNCLASSIFIED : The term "UNCLASSIFIED" or "NOT PROTECTIVELY MARKED" may be used in UK Government documents to indicate positively that a protective marking is not needed. Documents classified under the Protective Marking Scheme still exist and need correct handling. After 100 years all the classifications will have run out but the procedures may still be of interest to historians. ==Handling==