Function format_dimension 

pub fn format_dimension(
    value: f64,
    decimals: usize,
    tolerance: &ToleranceBlock,
    is_reference: bool,
    prefix: &str,
    suffix: &str,
) -> String

The dimension text: prefix (⌀ / R / "") + the nominal (+ the tolerance block) + suffix (° / ""); a reference dimension is parenthesized and shows no tolerance.