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Comment by rob74 | Hacker News Reader

If this "day 2" does not refer to an actual day (which does not have a real meaning if you're not on a planet), but to a phase, why do they call it "day" and not "phase"? Does "phase" have some kind of negative connotation, does it sound too "scientific"?

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I honestly don't know.

Just to clarify, the term "Day-2" isn't from NASA, it's a universal engineering term - which mostly happens on Earth ;)

I'm guessing it's just a planning term - like D-Day :shrugs:

* https://dzone.com/articles/defining-day-2-operations

* https://about.gitlab.com/solutions/day-2-ops/

Still doesn't explain why "Day" and not "Phase" or "Stage" or "Level" or "Period"

I think I covered the basic explanation in my article as well as dzone and gitlab did in theirs.

I think "day one" was an existing phrase that was confusingly extended to cover other "start of phase" concepts.

Sounds like a nice way to trick your management though, "Uh no, it won't have feature X on day one, but that will be working by Day-2."

I'll admit I've never heard of day 0/1/2 before.

I see Day-0, Day-1, Day-2 etc. used in the context of business planning quite frequently.

So its in 3 days?

I think the terms day 0/1/2 have caught on because they are constant across projects regardless how lacking or overboard the phase planning was. I.e. the project may or may not have much more detailed actual phases and those phases may or may not be obvious to someone without a background in the project but anyone can understand where the project is at without first ingesting the entire project plan.

Funny you would mention days being a constant for a space telescope on an orbit around the sun, where days definitely do not mean the same thing as they do on earth :)

See for example "day 1" (Bezos / Amazon):

https://www.forbes.com/sites/quora/2017/04/21/what-is-jeff-b...

(Not an edorsement / fandom.)

hmm maybe day 2 is after day 1 and before day 3 but not necessarily adjacent, meaning a specific day kicks something off any number of days after a previous planned day? So over the course of the next month we have 3 special days that kick off different phases.

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