From 1d6cddf3bb5e94c21321e01263e40804756035f4 Mon Sep 17 00:00:00 2001 From: ReaperOfVeriod Date: Sun, 11 Oct 2026 04:20:10 +0200 Subject: [PATCH] Identify the post-shrub region as a chunk container Range measured: level 0 post-shrub, 16047040..16737344, 690304 bytes. Method: scan for a 16-byte header ending 0xff, then 10 zero bytes, then a run of u32 whose top nibble is 0xF. Result: 28 chunk headers on level 0, present on all 27 levels. Each chunk is +0x00 16 bytes, last byte 0xff (opaque, differs per chunk) +0x10 10 zero bytes +0x1a N tagged offsets, top nibble 0xF Within a chunk the offsets step by a chunk-specific stride. On level 0: 148, 340, 368, 288, 320, 236, 272, 384, 116, 160, 250, 580, 576. Near-constant within a chunk, different between chunks. This resolves two earlier results, both of which were half-right. The 368-byte period is one chunk's stride, not a region property. That is why the region-wide autocorrelation is flat: ~15 strides averaging to noise. The 15360-byte window where 368 scored +0.315 is the third chunk at region+30066, whose stride is 368. The "ten-entry table" earlier disconfirmed is real. Chunks carry 5 to 30 tagged offsets, 10 most common on level 0. It was disconfirmed because I tested for a fixed 148 stride across a whole region; the table exists, but 148 is one chunk's stride among many. Both errors were the same one: reporting a local measurement as a regional property. Twice now. The control methodology caught neither, because a matched control bounds significance but says nothing about scope. Not decoded: the 16-byte header, the 0xF tag, where chunk data lives, and what any chunk means. Framing established, contents not. --- docs/formats/core-data-regions.md | 39 +++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md index ab38c29..d9e5cde 100644 --- a/docs/formats/core-data-regions.md +++ b/docs/formats/core-data-regions.md @@ -725,3 +725,42 @@ window holds 41/1841 of the region's records, and averaging that over the whole region flattens the peak to the noise floor. The re-verification pass checked the stride but not whether it applied uniformly, so it confirmed the number without testing the claim it was attached to. + +## The post-shrub region is a chunk container (explains the 368 stride) + +**Range measured:** level 0 post-shrub, 16047040..16737344 (690,304 bytes). + +**Method:** scan for the block shape `16-byte header ending 0xff` followed by +10 zero bytes followed by a run of `u32` whose top nibble is `0xF`. + +**Result: 28 chunk headers on level 0**, present on all 27 levels. Each chunk +is: + + +0x00 16 bytes, last byte 0xff (opaque; differs per chunk) + +0x10 10 zero bytes + +0x1a N tagged offsets, top nibble 0xF + +and within a chunk the offsets step by a **chunk-specific stride** — 148, +340, 368, 288, 320, 236, 272, 384, 116, 160, 250, 580, 576 all occur on +level 0. The stride is near-constant within a chunk (e.g. 148,148,148,148... +then 340,340,336,340...) but differs between chunks. + +**This resolves two earlier results.** + +The "368-byte period" is one chunk's stride, not a property of the region. +That is why the region-wide autocorrelation is flat: the region holds chunks +with ~15 different strides averaging out to noise. The 15,360-byte window where +368 scored +0.315 is the third chunk, at region+30066, whose stride is 368. + +The "ten-entry table" I earlier disconfirmed is real — chunks carry 5 to 30 +tagged offsets, with 10 the most common on level 0. It was disconfirmed because +I tested for a fixed stride of 148 across a whole region; the table exists, +but 148 is one chunk's stride among many. + +**Two corrections this produces.** Both earlier claims were half-right: real +structure, wrong scope. I reported a local measurement as a regional one in +both cases, which is the same mistake twice. + +**Not decoded.** What the 16-byte header is, what the `0xF` nibble tags, where +the chunk data lives, and what the chunk *means* are all open. The container +framing is established; its contents are not.