Exponent actually used for the Y values (-128 for float values).
exponentY keeps the raw subexp.
Raw subflgs byte (undefined bits are written by some software).
0-based position of the subfile in the file (indexNumber is the raw
subindx, a 16-bit value that wraps).
Y values were stored as IEEE float32.
OptionalnoisePeak-pick noise level, when subnois is set (high byte not 0).
Optionalplane0-based W plane (4D files whose planes divide the subfiles evenly).
OptionalwInterpreted W value (4D files only).
OptionalzInterpreted Z value (multifiles only; see zSpacing on the header).
OptionalzEnd of the Z interval (subnext) for ordered or random Z.
Metadata of one spectrum: the raw subheader and how its Y values were read.