<p>The terms <em>standard</em> and <em>non-standard</em> are specific to transactions. They have no application outside of that.</p>
<p>The terms <a href="https://bitcoin.stackexchange.com/questions/52528/how-is-a-standard-bitcoin-transaction-defined?rq=1">originate from the <code>IsStandard()</code></a> function in the original Bitcoin software. Originally, the following five transaction types were considered standard:</p>
<pre><code>P2PK, P2PKH, P2SH, P2MS, and OP_RETURN
</code></pre>
<p>The following were later added:</p>
<pre><code>P2WKH, P2WSH, P2TR
</code></pre>
<p>Anything other than these is non-standard.</p>
<p>Valid transactions are those that pass validity checks (e.g. matching UTXO(s) exist, script operates correctly).</p>
<p>It is possible for a transaction to be <a href="https://b10c.me/observations/09-non-standard-transactions/" rel="nofollow noreferrer">non-standard yet valid</a>.</p>
<p>There is discussion of validity vs standardness <a href="https://learnmeabitcoin.com/technical/script/#limits" rel="nofollow noreferrer">here</a>.</p>
<hr />
<p>The term <em>valid</em> or <em>validity</em> may also be applied more broadly; to a block or block header for example.</p>

CC BY-SA 4.0
2024-05-02T12:48:02.480Z
2024-05-02T13:17:42.847Z
2024-05-02T13:17:42.847Z
Lee
<p>In contexts outside of &quot;<a href="https://bitcoin.stackexchange.com/questions/120269/what-is-mempool-policy">mempool policy</a>&quot;, and broader than only transactions, what do the terms <em>non-standard</em> and <em>standard</em> mean (e.g. with reference to blocks, headers and well as transactions)?</p>
<p>How are they distinct from the term <em>invalid</em> ?</p>
<p>Are there any other terms or measures that might be used to refer to the &quot;standardness&quot; or validity of blocks, headers or transactions?</p>

CC BY-SA 4.0
2024-05-02T12:02:13.277Z
Does this answer your question? [What is "(mempool) policy"?](https://bitcoin.stackexchange.com/questions/120269/what-is-mempool-policy)
Antoine Poinsot
CC BY-SA 4.0
2024-05-02T12:18:55.037Z
@AntoinePoinsot possibly - you've a good answer there; does it still apply for contexts outside the mempool and more broadly than only transactions? (I have updated for this).
Lee
CC BY-SA 4.0
2024-05-02T12:26:12.663Z
@AntoinePoinsot Does "standardness" only apply to transactions?
Lee
CC BY-SA 4.0
2024-05-02T12:35:53.390Z
https://bitcoin.stackexchange.com/questions/52528/how-is-a-standard-bitcoin-transaction-defined?rq=1
Lee
CC BY-SA 4.0
2024-05-02T12:46:49.877Z
Yes, we only talk about standardness in the context of a transaction.
Antoine Poinsot
<terminology><block-validity><non-standard-transaction>
What is meant by "non-standard"?
Lee
# What is meant by "non-standard"?

(Asked by: username_0 on 2024-05-02)

In contexts outside of "[mempool policy](https://bitcoin.stackexchange.com/questions/120269/what-is-mempool-policy)", and broader than only transactions, what do the terms *non-standard* and *standard* mean (e.g. with reference to blocks, headers and well as transactions)?

How are they distinct from the term *invalid* ?

Are there any other terms or measures that might be used to refer to the "standardness" or validity of blocks, headers or transactions?

**Tags:** terminology, block-validity, non-standard-transaction

> **Comments:**
> **username_1**: Does this answer your question? [What is "(mempool) policy"?](https://bitcoin.stackexchange.com/questions/120269/what-is-mempool-policy)  
> **username_0**: @AntoinePoinsot possibly - you've a good answer there; does it still apply for contexts outside the mempool and more broadly than only transactions? (I have updated for this).  
> **username_0**: @AntoinePoinsot Does "standardness" only apply to transactions?  
> **username_0**: https://bitcoin.stackexchange.com/questions/52528/how-is-a-standard-bitcoin-transaction-defined?rq=1  
> **username_1**: Yes, we only talk about standardness in the context of a transaction.  

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## 1 answers

### Answer by username_0 on 2024-05-02. Score: 2 | Accepted answer

The terms standard and non-standard are specific to transactions. They have no application outside of that.
The terms originate from the IsStandard() function in the original Bitcoin software. Originally, the following five transaction types were considered standard:
P2PK, P2PKH, P2SH, P2MS, and OP_RETURN

The following were later added:
P2WKH, P2WSH, P2TR

Anything other than these is non-standard.
Valid transactions are those that pass validity checks (e.g. matching UTXO(s) exist, script operates correctly).
It is possible for a transaction to be non-standard yet valid.
There is discussion of validity vs standardness here.

The term valid or validity may also be applied more broadly; to a block or block header for example.


---

