diff --git a/docs/re/structures/slb-data-offset.md b/docs/re/structures/slb-data-offset.md
index f62cfcfe..ec7886d2 100644
--- a/docs/re/structures/slb-data-offset.md
+++ b/docs/re/structures/slb-data-offset.md
@@ -120,6 +120,37 @@ with a unique winner. `scan_data_offset` therefore falls back to 1392 on a tie.
 This is used only for the `RIFF`-less banks. Where a `RIFF` exists the offset is
 derived from it exactly, never scanned.
 
+### Is that 99.62 % transferable? — checked, and it is conservative
+
+The labelled set has a `RIFF`; the population the scan actually serves does not.
+Since the scan is unbounded it reads *past* the `RIFF` on labelled banks, so the
+99.62 % could have been borrowing discriminating power that a `RIFF`-less bank
+cannot offer. That would make the headline number optimistic for the only case
+it is used in — worth checking before trusting it.
+
+Confining the scan to the leading region drops it to **69.98 %** with 1 910
+ties, which at first looks like exactly that problem. It is not. Splitting by
+how much leading audio there is separates the two explanations:
+
+| | correct | ties |
+|---|---|---|
+| unbounded, all 7 358 labelled banks | 99.62 % | 28 |
+| confined to the leading region, all 7 358 | 69.98 % | 1 910 |
+| **≥24 packets of leading audio (989 banks), unbounded** | **100 %** | **0** |
+| **≥24 packets of leading audio (989 banks), confined** | **100 %** | **0** |
+
+The last two rows settle it. Where there is enough audio to score, the
+discriminator is perfect **whether or not the `RIFF` is in range** — so it is
+not leaning on the `RIFF`. The 69.98 % is an artifact of *short* leading
+regions: with only two or three packets to judge, candidates tie and the
+tie-break decides. Unboundedness helps those banks by giving the scan more bytes,
+which is why the two columns differ at all.
+
+A `RIFF`-less bank is a whole pak entry, tens of kilobytes, so 24 packets are
+always available — it is always in the 100 % regime. **The 99.62 % figure is
+therefore conservative for the population the scan is used on**, not optimistic.
+
+
 ## What this does not settle
 
 * **Why the offset takes those four values**, and what the bytes before it are.