Range measured: level 0, shrub class table, 7 entries at core index offset
10176. Six classes are bounded by a successor; the seventh runs to the end of
core_data and is excluded because its span contains the whole post-shrub
region.
Method: bound each span by the next class geometry offset, take the body from
data_offset to the span end, split into 8-byte records.
Result: 164 records across 6 bounded bodies, lengths 192 twice, 208 twice, 224,
240.
Per byte over those 164 records:
byte 0: 74 distinct, 60 zero byte 4: 72 distinct, 35 zero
byte 1: 58 distinct, 65 zero byte 5: 59 distinct, 38 zero
byte 2: 76 distinct, 43 zero byte 6: 1 distinct, 164 zero
byte 3: 62 distinct, 48 zero byte 7: 1 distinct, 164 zero
Bytes 6 and 7 are zero in every record; bytes 0 to 5 take 58 to 76 distinct
values with only 21 to 39% zero, so uniformly varied rather than sparse.
Read as u32 the fields are not plausible: u32[0] spans 0 to 4294871316 and no
field is monotone across the body. The six bytes are not two packed 32-bit
values.
This settles the six-varying-plus-two-constant shape on level 0 as a per-level
partition, rather than only in aggregate over the disc's 8938 records, which
is what rule 3a asks for. Two trailing zero bytes are padding or a flag pair.
Unresolved: whether the six bytes are six u8, an f32 plus two u16, or
something else. The u32 reading is excluded but no positive reading is
established.
Process note: the first attempt used ClassEntry and a hand-computed o_class
instead of ShrubClassEntry, and every ShrubHeader::region call failed. The
parser was fine; the caller was not.