re: the last keyframe time is the chunk terminator -- observed, not

assumed

Continuing the pulse's cycle length, which I had called a structural
limit of the format. It is, and now I can show it rather than assert it.

Dumping past what I thought was the final keyframe found an EIGHTH block:
fade 0x00ffffff at the same position, so the glow returns to fully
transparent and the pulse is a closed cycle rather than a one-shot ramp.
That is worth having on its own -- the port knows the animation ends
where it starts.

And the eighth block's time slot contains the four bytes "end ", the
record's ASCII terminator. So the corpus's rule that a group's last block
has no time of its own holds here in a second form: not the next group's
element index, but the chunk terminator. The value does not exist. That
goes into ui-rat-layout.md, because it generalises beyond this record.

The measured 2.3 s would need a final step of about 33 units. I have
written that number down explicitly labelled as fitted to the measurement
rather than read from the file, so nobody later re-derives it as a
decode.

One thing I had half-assumed and can now rule out: the word at +0x004 is
not a keyframe count. It reads 60 here with 8 keyframes and 30 in the
loop records with 3. Unknown, and marked so.

docs/re/structures/ui-rat-layout.md

@@ -695,4 +695,19 @@ rule, and the kind of moderate split that would be easy to over-read.
 rather than untried, and the field is at least correctly *sized*. Assigning
 meanings almost certainly needs the game observed with individual bundles
 loaded, not more static correlation — every property visible in the file has now
-been tried.
+been tried.
+
+## A leaf record's last keyframe time is the chunk terminator (2026-08-28)
+
+The build placement region's "a group's data stops 4 bytes short of its final
+block's time slot — that word is already the next group's element index" has a
+second form in **leaf `.rat` records**, where there is no next group.
+
+`ptbtn00f.rat` (`GP_TITLE` build 2, `RATC` at `0x04115e`) holds 8 keyframe blocks
+of the ordinary 40-byte layout starting at `+0x68`. The eighth block's time slot
+at `+0x1a4` contains **`end `** — the record's ASCII terminator. So the last
+keyframe's time is not merely unread, it is **not present**, and any animation's
+full cycle length has to come from measurement.
+
+❔ The word at `+0x004` is **not** the keyframe count: `0x003c0000` (60) with 8
+keyframes here, `0x001e0000` (30) with 3 in `ptloop01.rat`/`ptloop02.rat`.