I'm reading Franco's book "Understanding Bitcoin" and greatly enjoying it. Simultaneously I'm tailing a node log file. I notice the plethora of "nonstandard transaction: non-final"s. Franco says these are usually written by miners on bespoke node code bases. What are the main purposes of such transactions?

  • That message means that you're seeing a transaction on the network being relayed which is not yet valid in a block. They are nonstandard because we don't want them to fill up the mempool awaiting acceptance into a block. These are not transactions in blocks, they are not produced by miners. The most common cause is that your node is a bit behind in synchronization, so it's mistaken about what is acceptable. This corrects itself when it's synchronized. Apr 16, 2016 at 13:09
  • HI thanks for taking the time Pieter. I think this response may not be right. My understanding is that all unconfirmed (non-block) transactions which are not double spends will enter the mempool until such times as they become embodied in a block. Most are of course pay-to-address. Some are pay-to-pubkey. Some are multisig and P2SH and some OP_RETURN. The last of the types of transaction is the UNKNOWN tx, which is often called non-standard. It is said that one needs to write non-reference node code and run a miner which codes for unknowns. What do miners use this for? Apr 16, 2016 at 23:07
  • The type of transaction you're seeing is not really non-standard; they're just not being accepted due to being nonfinal, which means they have locktime that's set in the future. Apr 16, 2016 at 23:25
  • thanks again Pieter. bitcoin.stackexchange.com/questions/9165/… Gives more colour on the uses for transactions with dates set in the future. So I now know what those non-final transactions are about. However I still believe that there are such things as non-standard transactions which aren't non-final. These only ever get into blocks when blocks are created in nodes which have special modifications made to them to accept these non-standard transactions. I guess the headline question still remains: does anyone know typical uses for these in reality. Apr 17, 2016 at 1:56


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