<p>Transactions without <code>prev_out</code>s are known as coinbase transactions (not to be confused with transactions from the company named Coinbase) or coin generation transactions. They create outputs without needing any inputs to the transaction. Coinbase transactions are special transactions which are created miners and included as the first transaction in a block. They are what pays miners for their work.</p>

<p>There can only be one coinbase transaction per block, and it must be the first transaction of the block. The sum of the outputs must also meet certain constraints: it can be no more than the sum of the block subsidy and the sum of the transaction fees paid by all transactions in the block.</p>

CC BY-SA 3.0
2018-01-29T19:25:35.177Z
2018-01-29T19:25:35.177Z
Ava Chow
<p>I found some transaction inputs does not contain prev_out field, i.e. it does not have input address. It only has an output address. Does this mean this kind of transactions records the activities of mining new coins?</p>

<p>e.g.</p>

<pre><code>'tx': [{'hash': '2b1f06c2401d3b49a33c3f5ad5864c0bc70044c4068f9174546f3cfc1887d5ba', 'inputs': [{'script': '04ffff001d0138', 'sequence': 4294967295, 'witness': ''}], 'lock_time': 0, 'out': [{'addr': '1HwmP33SaknLYShXfjVU8KmVThU3JiuVgH', 'n': 0, 'script': '41045e071dedd1ed03721c6e9bba28fc276795421a378637fb41090192bb9f208630dcbac5862a3baeb9df3ca6e4e256b7fd2404824c20198ca1b004ee2197866433ac', 'spent': False, 'tx_index': 15066, 'type': 0, 'value': 5000000000}],
</code></pre>

<p>while for another transation:</p>

<pre><code>{'hash': 'ee475443f1fbfff84ffba43ba092a70d291df233bd1428f3d09f7bd1a6054a1f', 'inputs': [{'prev_out': {'addr': '1CfD77hupeUvFwBPxZ2fA8iyWmVwQY22oh', 'n': 1, 'script': '76a9147fe34b97aeff4ab754770be5c8f12e2e95332fd488ac', 'spent': True, 'tx_index': 8845778, 'type': 0, 'value': 10212000000}, 'script': '483045022100e5e4749d539a163039769f52e1ebc8e6f62e39387d61e1a305bd722116cded6c022014924b745dd02194fe6b5cb8ac88ee8e9a2aede89e680dcea6169ea696e24d52012102b4b754609b46b5d09644c2161f1767b72b93847ce8154d795f95d31031a08aa2', 'sequence': 4294967295, 'witness': ''}], ...
</code></pre>

<p>the second one has a <code>prev_out</code> field while the first one does not</p>

<transactions><blockchain><bitcoind>
transaction inputs does not have prev_out field
Jerry Xue
# transaction inputs does not have prev_out field

(Asked by: username_0 on 2018-01-29)

I found some transaction inputs does not contain prev\_out field, i.e. it does not have input address. It only has an output address. Does this mean this kind of transactions records the activities of mining new coins?

e.g.

```
'tx': [{'hash': '2b1f06c2401d3b49a33c3f5ad5864c0bc70044c4068f9174546f3cfc1887d5ba', 'inputs': [{'script': '04ffff001d0138', 'sequence': 4294967295, 'witness': ''}], 'lock_time': 0, 'out': [{'addr': '1HwmP33SaknLYShXfjVU8KmVThU3JiuVgH', 'n': 0, 'script': '41045e071dedd1ed03721c6e9bba28fc276795421a378637fb41090192bb9f208630dcbac5862a3baeb9df3ca6e4e256b7fd2404824c20198ca1b004ee2197866433ac', 'spent': False, 'tx_index': 15066, 'type': 0, 'value': 5000000000}],

```

while for another transation:

```
{'hash': 'ee475443f1fbfff84ffba43ba092a70d291df233bd1428f3d09f7bd1a6054a1f', 'inputs': [{'prev_out': {'addr': '1CfD77hupeUvFwBPxZ2fA8iyWmVwQY22oh', 'n': 1, 'script': '76a9147fe34b97aeff4ab754770be5c8f12e2e95332fd488ac', 'spent': True, 'tx_index': 8845778, 'type': 0, 'value': 10212000000}, 'script': '483045022100e5e4749d539a163039769f52e1ebc8e6f62e39387d61e1a305bd722116cded6c022014924b745dd02194fe6b5cb8ac88ee8e9a2aede89e680dcea6169ea696e24d52012102b4b754609b46b5d09644c2161f1767b72b93847ce8154d795f95d31031a08aa2', 'sequence': 4294967295, 'witness': ''}], ...

```

the second one has a `prev_out` field while the first one does not

**Tags:** transactions, blockchain, bitcoind


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## 1 answers

### Answer by username_1 on 2018-01-29. Score: 0 | Accepted answer

Transactions without `prev_out`s are known as coinbase transactions (not to be confused with transactions from the company named Coinbase) or coin generation transactions. They create outputs without needing any inputs to the transaction. Coinbase transactions are special transactions which are created miners and included as the first transaction in a block. They are what pays miners for their work.

There can only be one coinbase transaction per block, and it must be the first transaction of the block. The sum of the outputs must also meet certain constraints: it can be no more than the sum of the block subsidy and the sum of the transaction fees paid by all transactions in the block.


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