D Day
Q PLUS
Q+
“According to the U.S. military, “D-Day” was an Army designation used to indicate the start date for specific field operations. In this case, the “D” in D-Day doesn’t actually stand for anything—it’s merely an alliterative placeholder used to designate a particular day on the calendar. The military also employed the term “H-Hour” to refer to the time on D-Day when the action would begin…Military planners also used a system of PLUSSES and minuses to designate any time or day occurring before or after D-Day or H-Hour. For example, D+2 meant two days after D-Day, while H-1 referred to one hour before H-Hour. “
https://www.history.com/news/why-was-it-called-d-day