Outpoints are references to a ledger (UTXO set) entry.
An outpoint is formed by the SHA-256 of the transaction idem concatenated with the 4-byte LE serialized output index.
COutPoint(uint256 txIdemIn, uint32_t outIdx)
{
CSHA256Writer sha;
sha << txIdemIn << outIdx;
hash = sha.GetHash();
}