What is the meaning of the "spent" attribute of a transaction output? Looking at blockchain.info/tx/c52b....2b09?format=json, I see this:
[{
    &quot;spent&quot;:true,
    &quot;spending_outpoints&quot;:[
    {
        &quot;tx_index&quot;:0,
        &quot;n&quot;:0
    }
    ],
    &quot;tx_index&quot;:0,
    &quot;type&quot;:0,
    &quot;addr&quot;:&quot;1MLZEBnV8z7wKZnqUkkNWCaA7kohsvmkA2&quot;,
    &quot;value&quot;:493599,
    &quot;n&quot;:0,
    &quot;script&quot;:&quot;76a914df15522bd48e91e24d4ee94424ae0681ee7f1a1a88ac&quot;
},
{
    &quot;spent&quot;:false,
    &quot;tx_index&quot;:0,
    &quot;type&quot;:0,
    &quot;addr&quot;:&quot;3KcFQ3BxZzyPnq6VGW1LWjKnJZR6F3fYVS&quot;,
    &quot;value&quot;:106862,
    &quot;n&quot;:1,
    &quot;script&quot;:&quot;a914c48b6e8ee99bef36819e1d90365dea087075ba7187&quot;
},
&quot;...&quot;
]

I've assumed that every output was &quot;unspent&quot; when it is created. Here, it looks as if it is spent directly when the output is created? What does that even mean? Is it maybe spent in another transaction in the same block?
Or is that attribute added &quot;later&quot; by blockchain.info to give the reader a bit more context?
Or is that attribute added &quot;later&quot; by blockchain.info to give the reader a bit more context?

I'm pretty sure that is what is happening.
If you look at that transaction in a different explorer, for example https://blockchair.com/bitcoin/transaction/c52b5df64f10463fbe4f46d7b9da3464449849b7e542d533575a927366b52b09 and click &quot;raw tx&quot; you'll see it doesn't include that information in the JSON.