What Is the Practical Difference between "Opt-in RBF" and "Full RBF"? ▴ Learn

What Is the Practical Difference between “Opt-in RBF” and “Full RBF”?

The practical difference lies in the replacement policy of network nodes. Opt-in RBF (BIP125) requires the original transaction to explicitly signal its replaceability by setting the 'nSequence' field.

If the flag is absent, nodes generally won't relay a replacement. Full RBF is a node policy where any unconfirmed transaction, regardless of its RBF flag, can be replaced by a new, higher-fee transaction.

Full RBF maximizes the fee market but completely invalidates 0-conf security.

Can a Transaction Be Removed from the Mempool?

What Is “Replace-by-Fee” (RBF) and How Does It Affect Miners?

Can a Transaction Be Cancelled or Replaced Once It Enters the Mempool?

How Does RBF Relate to the Concept of “Transaction Malleability” in Cryptocurrency?