diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md
index 1b0f82d..e9a9997 100644
--- a/docs/formats/core-data-regions.md
+++ b/docs/formats/core-data-regions.md
@@ -2075,3 +2075,70 @@ and forgets the `* 100` reports "1.0%" for 99.4%. That happened here, in the
 diagnostic line only -- the assertions compare fractions and were always right --
 but it is the same family of error as everything else in this log: the readout
 disagreeing with the claim.
+
+## Tie slots 3, 6 and 7: what they are not
+
+Having established that `i16[0..2]` are positions, the remaining slots were
+attacked with two more measurements rather than by inspection.
+
+### Does slot 3 index a skeleton?
+
+`i16[3]` holds 201 distinct values in `0..=254`, and **50 distinct values within a
+single draw packet** (median, 1,804 records). A material or texture-set index
+would be constant per packet, so it is per vertex -- which invites the obvious
+reading: tie objects are skinned, and slot 3 is a joint index.
+
+That reading is wrong. If it named a joint, vertices sharing it would sit
+together. They do not:
+
+    mean pairwise distance, same slot-3 value        14,481
+    mean pairwise distance, different slot-3 value  13,795
+    ratio different/same                              0.95x
+    control: same position-x bucket                   8,105
+
+Vertices sharing a slot-3 value are if anything marginally *farther* apart than
+vertices differing in it -- 0.95x, the wrong side of neutral, though not far
+enough to claim much on its own. The control shows the measurement works:
+bucket by position-x and pairs collapse to 8,105, half the global distance.
+
+So slot 3 is not a skin index. It is also not shared across LODs: 75.3%
+same-class against a 78.7% control, i.e. no signal at all. Per-vertex, in
+`0..=254`, correlated with neither the geometry it sits in nor the detail level.
+**It is not understood**, and no reading is offered here. A per-vertex phase
+would fit the arithmetic, but that is a guess and is labelled as one.
+
+### Slots 6 and 7 are mostly not per-vertex
+
+Distinct values per draw packet, median over 1,804 records:
+
+| slot | median | constant for the whole packet |
+| --- | ---: | ---: |
+| `i16[0..2]` | 13-17 | 0% |
+| `i16[4]`, `i16[5]` | 6, 4 | 0% |
+| `i16[6]` | 2 | **43%** |
+| `i16[7]` | 4 | **34%** |
+
+`i16[6]` and `i16[7]` take a single value across the entire packet in well over a
+third of records, and two or three values in the median. Whatever they are, they
+are usually a property of the packet rather than of the vertex -- consistent with
+the 91.8%/88.9% dominance of 4096 and 0 respectively. They are left unnamed.
+
+### A note on why the per-slot LOD test does not generalise
+
+Run across all eight slots, the LOD1/LOD2 overlap test discriminates only on
+`i16[0..2]`:
+
+| slot | same class | control | ratio |
+| --- | ---: | ---: | ---: |
+| `i16[0]` | 97.0% | 3.0% | 32x |
+| `i16[1]` | 96.7% | 3.2% | 30x |
+| `i16[2]` | 96.4% | 6.0% | 16x |
+| `i16[3]` | 75.3% | 78.7% | 1x |
+| `i16[4..7]` | 68-91% | 52-79% | 1x |
+
+The other slots come from small value sets -- 226 to 1,759 distinct values across
+a level -- so two arbitrary sets of that size overlap heavily whether or not the
+field means anything. The test's power came from `i16[0..2]` being the only slots
+with tens of thousands of distinct values. **A passing result from a method that
+has run out of discriminative power is not a passing result**, and the 1x rows are
+recorded so the table is not later mistaken for nine confirmations.
diff --git a/docs/roadmap.md b/docs/roadmap.md
index ed40877..460de62 100644
--- a/docs/roadmap.md
+++ b/docs/roadmap.md
@@ -310,7 +310,13 @@ Phase 1 hands over the extents; this phase works out what each one contains.
       Within the all-zero case, `i16[3] == 0` exactly (5,851) is a third
       distribution at 62%. Three cases: `0x00/0x00`, `0x00/1..255`, and non-zero
       high byte.
-- [ ] The remaining tie vertex **fields are not named.** `i16[0..3]` span the full
+- [~] The remaining tie vertex **fields are not named**, and two readings are now
+      excluded. `i16[6]`/`i16[7]` are constant across a whole draw packet in
+      43%/34% of records, so they are usually per-packet rather than per-vertex.
+      `i16[3]` is per-vertex (50 distinct values per packet) but **not a skin or
+      joint index**: vertices sharing it are 0.95x *farther* apart than vertices
+      differing in it, against a control that halves. It is also unshared across
+      LODs. Recorded as not understood rather than guessed.
       `i16` range with 10,803-13,421 distinct values each. `i16[0..2]` are most
       likely position, but that is not established.
 - [~] `shrub` — class table done (48-byte entries, not 32; reading shrub at