The previous commit said "a mean of 6.99 of every 8 bytes are zero". That
is inverted. 6.99 is the mean count of live bytes, and the records are nearly
full rather than sparse. The live-byte histogram is 0:15, 2:1, 4:31, 5:238,
6:461, 7:1030, 8:1114.
That error also invalidated the reasoning built on it in this session's next
message, where the high zero-count was used to explain why the differential
analysis found no constant positions. There was no zero-density to explain.
The differential result stands -- all 8 positions vary -- but for the plain
reason that the records are dense, not because of any artifact.
New finding from re-examining it: byte 7 takes only 14 distinct values where
bytes 0-6 take 142-204. Its common values are 0x00 (1378), 0xff (806) and
0x80 (592), which are the high bytes of signed 16-bit values. That is
consistent with byte 7 being an MSB rather than ordinary data. Unexplained.
Also tried and recorded as not helping: a signed 16-bit reading spans
-32743..32633, near the full range, with no per-position structure (533, 371,
401 and 187 distinct at positions 0-3).
ReaperOfVeriod
0ba790df1f