Dimension — time
What held then, and what you knew at the time.
Two clocks, not one. Most systems keep effective dates on some records and an audit log on others; few let one question pin both clocks across everything.
There are two different times in every operational statement, and conflating them is a common modelling mistake.
When it was true is world time. The part sat on that shelf from March to September. The technician was qualified from January. The work package was open across that window. And for an aircraft, time is also flight hours and cycles, carried as measured quantities with their units.
When you knew it is knowledge time. You found out on Tuesday. The correction arrived three weeks later. The import that said otherwise ran overnight.
Keep only the first and you cannot show what a decision stood on — you will always judge June with October’s information. Keep only the second and a late fact is filed under the wrong date: you cannot ask what was true in March as you know it now, or what is planned for May. Selira keeps both, and a question may pin either.
Looking back
The audit question is a knowledge question
Your technical records already keep what was signed, and when. What they do not keep is what the other systems, the planner’s sheet and the supplier’s email said that morning — so a decision looked at two years later is read against today’s corrected picture.
With knowledge time, a decision is readable as of the moment it was taken: the statements held then, and when each correction arrived afterwards. When an occurrence is investigated, that is what you are asked to show.
It has honest limits. It runs forward from the day Selira holds a record, and today an import can set when something was known — so it is a reading of what was held, not a sealed record; a third clock the system stamps itself, which nobody can set, is where it is going. And it shows which statements were held at a moment, the grain decisions are made at — not the value of every field at every instant.
It runs today, on sample data. Proving it at the volume of a whole airline — with space, truth and source in the same question — is what we are working on right now, and the numbers will be on this page.
What you can ask
- As of
- Where was this, and what state was it in, on the fourteenth of November?
- As known
- What did we believe that morning, before the correction came in?
- Over
- Show me this unit's whole history back to birth: every installation, removal and shop visit, as one timeline.
- Ahead
- What is planned to be true on the date I need it, and who planned it?
Read a decision as it stood on the day.
Bring one you had to explain. We will model it and show what it stood on.