As a bundle is made of 4 or more transactions, and a bundle is accepted as a whole or not at all, is a bundle treated as a single tip by subsequent transactions, or is it treated as 4 tips, that are each confirmed independently?

  • 1
    Hi Slicc, it's unclear if you're referring the the composition of a bundle from a mechanical standpoint, or the composition of a transaction from a confirmation standpoint of referencing two previous transactions, which then forms a single new tip.
    – aboose
    Commented Dec 23, 2017 at 22:59

1 Answer 1


A bundle can also have only 1 transaction (zero value tx), 3 transactions (if there is no remainder, therefore no change address) or more transactions (if there is a remainder and/or there are multiple output addresses).

The transactions in a bundle are always linked via trunk transaction hash (so trunk transaction hash of the first transaction in a bundle points to the second one, and so on). Therefore, only the first transaction (the "tail transaction") appears as a tip (the others are not tips as they have already one transaction that approves them), and the tip selection process will never stop at a transaction that is not the tail transaction (since when there is at least one consistent transaction that approves the current transaction, MCMC walk will never stop; and whether a transaction is consistent is the same for the whole bundle).

So when you look at a tangle explorer, you will see all the transactions as individual ones; but from the "tip selection" point of view, they will not be selected in practice, so you could as well ignore it.

  • Great that makes sense.
    – Slicc
    Commented Dec 24, 2017 at 6:08

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