GateTrue

What each generator documents about marking its output

Re-reading: maintenance that leaves a date behind

A re-reading is opening a source page again to check a value. It moves the reading date, leaves the value-since date alone, and is the only thing that keeps a register from becoming a snapshot. As of 2026-09-22.

Three outcomes of opening a source page againIf the statement is unchanged, the reading date moves and nothing else does. If the value has changed, both dates move and the row keeps its handle so the change is traceable. If the page has been redesigned, the reading has to be performed again rather than confirmed.What is found when the page is opened againThe same statementA confirmationThe reading date moves totoday; the value-sincedate stays where it was.A different statementA changeBoth dates move, thehandle stays, and arevision records whatmoved.A redesigned pageA new readingThe evidence was arelationship between partsof a layout that no longerexists.Only one of these three is cheap
Fig. 1 A confirmation on a redesigned page would be a guess wearing a date, which is what the evidence class exists to prevent.
How this register uses the term, and what it excludes. Written 2026-09-22.
The termRe-reading
What it namesOpening a source page again to confirm a value
What it is notRecording the same value from a different source
Where the register uses itEvery value whose two dates differ

Inclusion rule. Words this site uses in a narrow sense, where the ordinary sense would lead a reader to misread a cell. No vendor statement appears on this page. Order. Fixed order: what the word names, what it excludes, then where it is used here.

1What it costs depends on the evidence class

Confirming a sentence is looking for a clause: fast, reliable, and easy to do at scale. Redoing a layout reading means establishing which columns exist, what is inherited and whether a glyph carries the meaning, which is slower and easier to get wrong.

So the classes predict maintenance cost as well as durability. A register with many layout readings needs more work per cycle than one built on sentences, and the readings say which values are in which class so a reader can judge that.

2When a re-reading is not enough

Where a page has been redesigned, checking is not the operation. The reading has to be performed again from scratch, because the evidence was a relationship between parts of a layout and the layout has changed. A confirmation in that situation would be a guess wearing a date.

That is the case the evidence class exists to flag. A row marked as carried by layout is a row that needs the full job whenever the page moves, which is a different commitment from a row built on a clause.

3Why it does not touch the other date

If a confirmation moved the value-since date, the register would lose all record of duration and a long-standing statement would be indistinguishable from a new one. Keeping one date still is what makes a genuine change visible when it happens.

A re-reading that finds a different value is not a confirmation at all: both dates move, the row keeps its identifier, and the change is what a revision records. The identifier is what makes that traceable rather than looking like a new row.

Nothing on this page is a vendor statement; the values it helps read are on the support table, with the page and the date each one was read from. See also the protocol page, what earns a row. Nearby terms: register row, inclusion rule, re-encode.