Macro num_element 

macro_rules! num_element {
    ($(#[$meta:meta])* $name:ident) => { ... };
}

Define an X12 numeric data element (R decimal or N numeric).

Stores the raw text exactly (so "007", "5.00", "+5" all round-trip byte-for-byte and never lose precision or format) and exposes typed views via as_f64() / as_i64(). Named by X12 element number (e.g. E739).