Function document_token_payment_extra_sighash_data_v0 

pub fn document_token_payment_extra_sighash_data_v0(
    token_id: &[u8; 32],
    owner_id: &[u8; 32],
    data_contract_id: &[u8; 32],
    document_id: &[u8; 32],
    amount: u64,
) -> Vec<u8> 

Version 0 layout: token_id (32) || owner_id (32) || data_contract_id (32) || document_id (32) || amount (8, little endian). Frozen: never mutate; a layout change requires a new _v1 + version bump.