I see two ways:
Txid + index
Txid + script hash
Pros of the txid + index:
- Simple and short
Cons of txid + index:
- It relies on array iteration being deterministic and all third party services using the same iteration method.
Txid + script hash does not rely on iteration order and since script hashes are stored on the blockchain they are not malleable after 6 confirmations.
Which would be the preferred way to go?