Function parse_spread_section 

pub fn parse_spread_section<'a>(
    lines: &mut impl LineStream<'a>,
    header: &FrameHeader,
    atom_data: &mut [AtomDatum],
) -> Result<bool, ParseError>

Spreads: per-atom root-mean-square spread [sx, sy, sz] (Angstrom, each non-negative), same layout as velocities/forces.