How current a record is
Every record carries a class, and each class carries a review interval. A record whose as-of date is older than its interval is marked past review in its evidence bar. The marker says the record is due a re-read; it does not say the record is wrong.
Raw age is not shown, because fifty years means opposite things for a diffraction relationship and a launch price. The interval is set by what kind of thing the record states, and one class, physical relationships, never expires.
| Class | Review interval |
|---|---|
| PHYSICS | does not expire |
| ENGINEERING-MEASURED | 5-year |
| ARCHITECTURE | 3-year |
| ENVIRONMENT | 3-year |
| REGULATORY | 1-year |
| COST | 1-year |
| ECONOMIC | 2-year |
| PROGRAMME | 6-month |
| CORPORATE | 6-month |
| VOICE | 1-year |
| FORECAST | 1-year |
Two markers, two different facts
past review means the class has an interval and the record's date is beyond it. no review interval means the record's class is not in the table above, so how current it is cannot be computed from its date at all. The second is rarer and is a gap in the register's own vocabulary rather than in the record.
A record is never removed for being past review. It stays published, marked, until it is re-read and either confirmed with a new date or corrected. What the marker changes is how much weight to give a figure that depends on the year it was made.