<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**: @username_1 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**: @username_1 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.  

---

## 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()`](https://bitcoin.stackexchange.com/questions/52528/how-is-a-standard-bitcoin-transaction-defined?rq=1) 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](https://b10c.me/observations/09-non-standard-transactions/).

There is discussion of validity vs standardness [here](https://learnmeabitcoin.com/technical/script/#limits).

---

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


---

