H-Hour

The military designation of days and hours within the North Atlantic Treaty Organisation (NATO), is specified in AAP-6 (STANAG 3680), NATO Glossary of Terms and Definitions, and marked (NATO) in what follows. Those entries marked (US) are specific to the U.S., and defined only in Joint Publication JP 1-02, Department of Defense Dictionary of Military and Associated Terms.

References to days (or hours) preceding or following a designated day (or hour) use a plus or minus sign and an Arabic numeral following the letter. For example, "D−3" is 3 days prior to D-day, "C+7" is 7 days after C-day, "H−2" is 2 hours before H-hour, and so forth. In less formal contexts, the time is usually spelled out, so that "D−3" becomes "D minus three" or "D minus 3".

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