Function pio_source_format 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn pio_source_format(
    net: *const PioNetwork,
    out: *mut c_char,
    cap: usize,
) -> usize

Source format enum spelling used by the JSON snapshot, for example Matpower, PowerModelsJson, or Normalized. Uses the same cap/count string convention as pio_network_name.