user7269: Is it possible to attach a public note to transaction using Electrum client, if yes so how ?

user34469: No, that's not possible.
Public notes are a feature of blockchain.info and only exist in the blockchain.info database (and not in the Bitcoin blockchain).
The only way to add a public note to a transaction on blockchain.info seems to be by using their wallet.

7269: <p>Is it possible to attach a public note to transaction using Electrum client, if yes so how ?</p>
 34469: <p>No, that's not possible.</p>

<p>Public notes are <a href="https://blockchain.info/wallet/website-faq" rel="nofollow">a feature of blockchain.info</a> and only exist in the blockchain.info database (and not in the Bitcoin blockchain).</p>

<p>The only way to add a public note to a transaction on blockchain.info seems to be by using their wallet.</p>
