diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md
index a1cac0d..079a97c 100644
--- a/docs/formats/core-data-regions.md
+++ b/docs/formats/core-data-regions.md
@@ -3383,3 +3383,49 @@ That gap is the artifact, and naming both denominators is the most useful thing
 this section can do about it. A percentage over vertices and a percentage over
 distinct values answer different questions, and only one of them was ever asked
 about.
+
+
+## The tie vertex stride, searched properly: 64 where one exists, none for 62%
+
+The 16-byte reading was retracted without a replacement. Searching for one: for
+every tie vertex region, try strides 4, 8, ... up to `len / 16` and keep any where
+some byte offset is constant across every unit.
+
+    regions examined                1,844
+    no stride found at all            1,139   (61.7%)
+    stride 64                           491
+    stride 56                           120
+    stride 72                            49
+    stride 48                            12
+    stride 16                             3
+
+**64 bytes, not 16, wherever a stride is detectable** -- and for more than three in
+five regions there is no stride in range that produces a single constant byte.
+Those regions are genuinely variable, or the element is larger than the region
+divided by sixteen units, which is the same statement.
+
+### The control that changed the answer
+
+The first run of this search reported **1,561** regions at stride 64. It was
+wrong, and wrong in a way worth recording: a large stride divides a region into
+fewer units, and fewer units makes an accidental constant more likely. Length is
+fixed across strides, so the widest candidate always has the fewest units and the
+best chance of constancy by luck alone.
+
+Requiring every candidate stride to cover the **same** minimum of 16 units, and
+preferring the **smaller** stride when hit counts tie, drops it to 491 and
+promotes 56 and 72 into view -- which were invisible before.
+
+That is rule 3a's sampling failure in its purest form: an aggregate over
+candidates with different denominators, where the largest denominator wins for a
+reason that has nothing to do with the data. The first number was not merely
+imprecise, it was reporting the artefact.
+
+### What this does not settle
+
+64 is the stride where one is detectable, which is not the same as the stride.
+For the 1,139 regions with no constant byte under any tested stride, the element
+is still unknown, and the tie vertex layout remains open. What is settled is that
+**16 is not it** -- only 3 of 1,844 regions show a constant byte at 16 -- which is
+the quantitative version of the retraction, and a third independent measurement
+now agreeing with it.