diff --git a/docs/re/structures/slb-data-offset.md b/docs/re/structures/slb-data-offset.md
index 129a0e1e..0f5e840d 100644
--- a/docs/re/structures/slb-data-offset.md
+++ b/docs/re/structures/slb-data-offset.md
@@ -392,3 +392,47 @@ What survives:
 * ❌ Both my "69.8 % are truncated" and my attempted reversal of it are off the
   table. The measured fact is unchanged and narrow: **the declared `data` size
   exceeds the TOC window for 5 296 of 7 586 banks.**
+
+
+## ❔ The `seek` chunk's layout — identified, but it does not yield a packet count
+
+The decoder-independent boundary signal this page called for is the `seek`
+chunk. Its **shape** is now readable; its **arithmetic** is not.
+
+Immediately after the `seek` tag sits a little-endian size, then a short header,
+then a strictly ascending table:
+
+    eng\etc\VOICE_D_452     seek at +3 440   size 64    -> 16 words
+    eng\Voice\VOICE_TCAF_592 seek at +9 660   size 108   -> 27 words
+    eng\Voice\VOICE_TCAF_608 seek at +28 092  size 348   -> 87 words
+
+    words after seek+8 (big-endian):
+      0x01000000, <varies>, 0, then ascending: 0, 1572864, 3932160, 6160384, ...
+
+Word 0 is `0x01000000` in every bank examined — a version or entry-size marker.
+Word 1 varies and its top byte is 14 / 25 / 85 for the three above. Word 2 is 0,
+and the ascending run begins after it.
+
+**Two readings tried, both fail:**
+
+| reading | D_452 | TCAF_592 | TCAF_608 |
+|---|---|---|---|
+| declared `data` size ÷ 2048 (packets) | 13 | 17 | 371 |
+| `seek` size ÷ 4 (entries) | 16 | 27 | 87 |
+| entries − 3 header words | **13 ✅** | 24 ✗ | 84 ✗ |
+
+The third row is the near-miss that would be easy to adopt: it is exactly right
+for `VOICE_D_452` and wrong for the other two. That is a one-of-three fit, and
+this page has already recorded two measurements today that returned plausible
+numbers for questions they could not answer — so it is recorded as **failed**,
+not as a rule with exceptions.
+
+The ascending values are not packet indices: the steps (≈1.5–2.2 million) are far
+too large for a bank of a few hundred packets, so they are sample or
+fixed-point offsets on some other scale that has not been identified.
+
+**What the next attempt should know**: the chunk is real, its size field is
+little-endian, three header words precede the table, and the entry count is
+*not* the packet count. `auto/slb-loader` reports chaining `seek` packet counts
+successfully across consecutive entries — whatever field it used is not one of
+the two tried here, and reconciling the two readings is the cheapest way in.