Function blocks_at 

pub fn blocks_at<Tz>(
    rich: &RichText,
    reading: &Reading<Tz>,
) -> Vec<BlockContent>
where
    Tz: TimeZone,

The blocks rich text shows as for reading: each reference as the text says it reads for the person (reference_label), each time as it reads for them (time_label); paragraph ids are their places.