From 0f1a7f27c7feb9fc46b605ac8a434777f57fa2c3 Mon Sep 17 00:00:00 2001 From: ReaperOfVeriod Date: Sun, 11 Oct 2026 04:06:42 +0200 Subject: [PATCH] Resolve the SBlk discrepancy: 40 is the record, markers are nested A fine scan settles it in favour of 40: stride 40 +0.454 stride 39 +0.266 stride 41 +0.215 stride 38 +0.214 The peak is sharp and isolated, nearly twice its immediate neighbours, and the multiples confirm it: 80 scores +0.376, 120 +0.394, 160 +0.340, while the multiples of 12 (24, 48, 96, 144) all sit at 0.21 to 0.24. So the record is 40 bytes and the 0x7f/0x47f markers at 12-byte spacing are a nested structure inside those records, not the record boundary. Their spacing is irregular -- 12, 24 and larger -- which is what one would expect of a field present in some records and absent in others. The previous commit's "they disagree" framing was itself wrong in one respect: the marker spacing never claimed to be the record size. Read as a claim about markers inside records rather than about the record itself, the two measurements were never in conflict, and I had set up a false dichotomy between them. --- docs/formats/core-data-regions.md | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md index ce97e3d..4c8557f 100644 --- a/docs/formats/core-data-regions.md +++ b/docs/formats/core-data-regions.md @@ -592,7 +592,28 @@ explaining the other. Recorded as an open discrepancy rather than resolved in favour of either: the marker spacing says 12, the period says 40, and 40 being twice as strong is the more surprising of the two. -This is the first place in this project where two sound measurements of the -same data point at incompatible answers. Worth resolving before any record -layout is attempted, because a layout built on the wrong one will parse -plausibly and be wrong. +### Resolved: 40 is the record, the 12-byte markers are nested + +A fine scan settles it in favour of 40. + +| stride | excess | +|---|---| +| **40** | **+0.454** | +| 39 | +0.266 | +| 41 | +0.215 | +| 38 | +0.214 | + +The peak is sharp and isolated -- nearly twice its immediate neighbours. +And the multiples confirm it: 80 scores +0.376, 120 +0.394, 160 +0.340, +while the multiples of 12 (24, 48, 96, 144) all sit at 0.21-0.24. + +So the record is **40 bytes**, and the `0x7f`/`0x47f` markers at 12-byte +spacing are a nested structure *inside* those records rather than the record +boundary. Their spacing is irregular -- 12, 24 and larger -- which is exactly +what one would expect of a field that is present in some records and absent in +others. + +The earlier "they disagree" framing was wrong in one respect: the marker +spacing never claimed to be the record size. Read as a claim about markers +inside records rather than about the record itself, the two measurements were +never in conflict.