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I regularized the descriptions in the localfeatures table, so keep a careful eye on the accuracy of those. Otherwise, fairly standard editing in this very short section. Added text for lack of globalfeatures flags.
41 lines
2.5 KiB
Markdown
41 lines
2.5 KiB
Markdown
# BOLT #9: Assigned Feature Flags
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This document tracks the assignment of `localfeatures` and `globalfeatures` flags in the `init` message ([BOLT #1](01-messaging.md)), as well as the `features` field in the `channel_announcement` message and `node_announcement` message ([BOLT #7](07-routing-gossip.md)).
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They are tracked separately since new flags will likely be added over time.
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The `features` flags in the routing messages are a subset of the `globalfeatures` flags, since the `localfeatures` are by definition only of interest to direct peers.
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Flags are numbered from the least-significant bit, at bit 0 (i.e. 0x1,
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an even bit). They are generally assigned in pairs so that features
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can be introduced as optional (odd bits) and later upgraded to be compulsory, refusing
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old nodes (even bits). See [BOLT #1: The `init` Message](01-messaging.md#the-init-message).
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## Assigned `localfeatures` flags
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These flags may only be used in the `init` message:
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| Bits | Name |Description | Link |
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|------|------------------|------------------------------------------------|---------------------------------------------------------------------|
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| 0/1 | `option-data-loss-protect` | Requires or supports extra `channel_reestablish` fields | [BOLT #2](02-peer-protocol.md#message-retransmission) |
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| 3 | `initial_routing_sync` | Indicates that the sending node needs a complete routing information dump | [BOLT #7](07-routing-gossip.md#initial-sync) |
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| 4/5 | `option_upfront_shutdown_script` | Commits to a shutdown scriptpubkey when opening | [BOLT #2](02-peer-protocol.md#the-open_channel-message) |
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## Assigned `globalfeatures` flags
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There are currently no `globalfeatures` flags.
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## Requirements
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The requirements for receiving specific bits are defined in the linked sections in the table above.
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The requirements for feature bits that are not defined
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above can be found in [BOLT #1: The `init` Message](01-messaging.md#the-init-message).
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## Rationale
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There's little point in insisting on an `initial_routing_sync`. You can't
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tell if the remote node complies, and it has to know what the flag means as
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it's defined in the initial spec. So, there's no even bit for this.
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<br>
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This work is licensed under a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by/4.0/).
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