Add a BIP to define 24 bits of nVersion as nonce space not 16 #2116

1. 
   TheBlueMatt commented at 11:50 am on March 5, 2026: contributor
2. Add a BIP to define 24 bits of nVersion as nonce space not 16 e1ac2e7ab1
3. in bip-XXXX.mediawiki:4 in e1ac2e7ab1

   0@@ -0,0 +1,43 @@
   1+<pre>
   2+  BIP: ?
   3+  Title: 24 nVersion bits for general purpose use
   4+  Author: Matt Corallo <bips@bluematt.me>
   

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   murchandamus commented at 6:02 pm on March 5, 2026:

   0  Authors: Matt Corallo <bips@bluematt.me>
   

4. in bip-XXXX.mediawiki:7 in e1ac2e7ab1

   0@@ -0,0 +1,43 @@
   1+<pre>
   2+  BIP: ?
   3+  Title: 24 nVersion bits for general purpose use
   4+  Author: Matt Corallo <bips@bluematt.me>
   5+  Status: Draft
   6+  Type: Specification
   7+  Created: 2026-02-26
   

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   murchandamus commented at 6:03 pm on March 5, 2026:

   0  Assigned: ?
   

5. in bip-XXXX.mediawiki:27 in e1ac2e7ab1

   22+
   23+24 bits from the block header nVersion field, starting from 5 and ending at 28 inclusive (0x1fffffe0), are reserved for nonce use and removed from BIP8 and BIP9 specifications. A mask of 0xe000001f should be applied to nVersion bits so bits 5-28 inclusive will be ignored for soft-fork signalling and unknown soft-fork warnings.
   24+
   25+==Rationale==
   26+
   27+Headers-only mining avoids mining devices (either ASICs or the firmware) from having to concern itself with the vast space of consensus logic (handling transactions, merkle trees, etc). It is widely deployed in ASICs, but requires a substantial number of jobs fed across an entire device, keeping the ASIC controller busy. Providing additional nonce space for the ASICs to roll without needing fresh work from the controller may simplify ASIC design somewhat, and as been apparently adopted in some miners by using extra space in nTime as extra nonce space. Doing so in nVersion instead is preferable to using nTime.
   

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   murchandamus commented at 6:05 pm on March 5, 2026:

   0Headers-only mining avoids mining devices (either ASICs or the firmware) from having to concern themselves with the vast space of consensus logic (handling transactions, merkle trees, etc). It is widely deployed in ASICs, but requires a substantial number of jobs fed across an entire device, keeping the ASIC controller busy. Providing additional nonce space for the ASICs to roll without needing fresh work from the controller may simplify ASIC design somewhat, and has been apparently adopted in some miners by using extra space in nTime as extra nonce space. Doing so in nVersion instead is preferable to using nTime.
   

   Also, for legibility of review comments, it would be preferable if you limited the length of the lines in the document.

6. in bip-XXXX.mediawiki:9 in e1ac2e7ab1

   0@@ -0,0 +1,43 @@
   1+<pre>
   2+  BIP: ?
   3+  Title: 24 nVersion bits for general purpose use
   4+  Author: Matt Corallo <bips@bluematt.me>
   5+  Status: Draft
   6+  Type: Specification
   7+  Created: 2026-02-26
   8+  License: BSD-3-Clause
   9+           CC0-1.0
   

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   murchandamus commented at 6:09 pm on March 5, 2026:

   Since BIP3 deployed, we are using License Expressions for the License header values: https://github.com/bitcoin/bips/blob/master/bip-0003.md#specification-1

   0  License: BSD-3-Clause OR CC0-1.0
   

7. in bip-XXXX.mediawiki:39 in e1ac2e7ab1

   34+
   35+==Acknowledgements==
   36+
   37+Timo Hanke and Sergio Lerner for originally proposing 15-bit extra nNonce2. Btc Drak for writing BIP 320.
   38+
   39+==Changelog==
   

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   murchandamus commented at 6:11 pm on March 5, 2026:

   Nit: It would be preferable to only add this section when it has content.
8. in bip-XXXX.mediawiki:10 in e1ac2e7ab1

    5+  Status: Draft
    6+  Type: Specification
    7+  Created: 2026-02-26
    8+  License: BSD-3-Clause
    9+           CC0-1.0
   10+  Replaces: 320
   

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   murchandamus commented at 6:14 pm on March 5, 2026:

   I saw that this was discussed on the mailing list. Please add a Discussion header:

   0  Discussion: 2026-02-26: https://gnusha.org/pi/bitcoindev/6fa0cb45-37d6-4b41-9ff8-03730fd96d6e@mattcorallo.com/
   1  Replaces: 320
   

   Please also add the corresponding Proposed-Replacement header to BIP 320.

9. murchandamus added the label New BIP on Mar 5, 2026
10. murchandamus added the label PR Author action required on Mar 5, 2026

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