diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8da14e3..69e4484 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -261,6 +261,24 @@ proposed; any of them that is taken lands as an editor change recorded here.
 
 ### Clarified
 
+- **§4 — a `top_ngrams` `sequence` is `ngram_size` consecutive records of one
+  observation stream.** §4 sized the block by `ngram_size` (*"size of n-grams"*) and
+  described a *"sequence/transition fingerprint"*, but never said what a sequence IS, so
+  a producer could read it as any template-to-template relation it observes. A new
+  sentence under the example says it: the template ids of `ngram_size` consecutive
+  records of one observation stream, in observation order, so every entry holds exactly
+  `ngram_size` ids. What a producer treats as one observation stream (the whole window,
+  or a narrower scope such as one trace) stays its own; the sentence names no scope.
+  The probability paragraph loses the clause about a `top_ngrams` holding sequences of
+  more than one length, which no conforming document can now hold, and reads n as
+  `ngram_size`. The clause was added in this unreleased 0.10.0 line, after the
+  reference implementation was found putting a second relation (a declared link between
+  two records, not their adjacency) into the block at `ngram_size` 3; that producer now
+  carries such relations in `extensions` (§7), which is where a relation another
+  producer would not compute from the same records belongs. **Against every released
+  version this changes no document's validity**; against the unreleased 0.10.0 draft it
+  withdraws a clause that admitted two lengths. No schema changed.
+
 - **§8 — clause 2 is mechanically decidable for `window` (§2.2), and the closing
   paragraph now says so.** It read *"clauses 2 and 3 are not mechanically decidable
   today: clause 2 only as far as the schema expresses it"*. That understated what is
diff --git a/SPEC.md b/SPEC.md
index ac6ba35..7c96d71 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -807,7 +807,7 @@ Captures *how* templates follow each other, beyond raw frequency.
   "ngram_size": 2,                     // integer, required, size of n-grams (2 = bigrams)
   "top_ngrams": [                      // array, required, ordered by count desc
     {
-      "sequence": ["h:8a3f...", "h:b104..."],  // array of template_ids
+      "sequence": ["h:8a3f...", "h:b104..."],  // array of ngram_size template_ids — see below
       "count": 8421,
       "probability": 0.677              // p(last | first n−1), among sequences of this length — see below
     }
@@ -829,15 +829,17 @@ Captures *how* templates follow each other, beyond raw frequency.
 }
 ```
 
+**`sequence` — consecutive records of one observation stream.** An entry's `sequence`
+is the template ids of `ngram_size` consecutive records of one observation stream, in
+observation order, so every entry of `top_ngrams` holds exactly `ngram_size` ids.
+
 **`probability` — a conditional, never a joint.** An entry's `probability` is
-p(last | prefix): its `count` divided by the summed `count` of every sequence **of the
-same length** the producer counted in the window whose first n − 1 template ids equal
-the entry's own, n being the length of the entry's `sequence`. At `ngram_size` 2 it is
-p(next | prev); at 3 it is p(third | first two). It is computed over every counted
-sequence, **before** the `top_ngrams_size` cut, so the retained entries sharing a
-prefix need not sum to 1. A sequence of another length never enters the sum: in a
-`top_ngrams` holding sequences of more than one length, each length is conditioned
-among its own. It is a conditional and not a joint probability because frequency is
+p(last | prefix): its `count` divided by the summed `count` of every sequence the
+producer counted in the window whose first n − 1 template ids equal the entry's own,
+n being `ngram_size`. At `ngram_size` 2 it is p(next | prev); at 3 it is
+p(third | first two). It is computed over every counted sequence, **before** the
+`top_ngrams_size` cut, so the retained entries sharing a prefix need not sum to 1.
+It is a conditional and not a joint probability because frequency is
 already carried by `count`, and because §13's `ngram_delta.rate_changed` compares this
 value across two windows as a transition RATE: a joint value would move with any change
 in traffic mix and would mean a different quantity at each `ngram_size`.