A reference input (similar to UTxO, but without information about original transaction output).

Needed for tx.addRefInput() and tx.addRefInputs().


A TxRefInput instance is constructed using the TxId where the UTxO was created, and the index of that UTxO in the list of UTxOs created by that transactions.

new helios.TxRefInput(
    txId: TxId,
    utxoIdx: bigint