designation of days and hours

The following designations have the meaning shown: D-day*--The day on which an operation commences or is due to commence. This may be the commencement of hostilities or any other operation. E-day*--The day on which a NATO exercise commences. G-day--The day on which an order, normally national, is given to deploy a unit. K-day*--The day on which a convoy system is introduced or is due to be introduced on any particular convoy lane. M-day*--The day on which mobilization commences or is due to commence. H-hour*--The specific time at which an operation or exercise commences, or is due to commence. (*This term is used also as a reference for the designation of days/hours before or after the event.) (DOD only: See also times; wartime manpower planning system.)