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BOLT #9: Assigned Feature Flags
This document tracks the assignment of localfeatures and globalfeatures flags in the init message (BOLT #1), as well as the features field in the channel_announcement message and node_announcement message (BOLT #7).
They are tracked separately since new flags will likely be added over time.
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.
Flags are numbered from the least-significant bit, at bit 0 (i.e. 0x1,
an even bit). They are generally assigned in pairs so that features
can be introduced as optional (odd bits) and later upgraded to be compulsory, refusing
old nodes (even bits). See BOLT #1: The init Message.
Assigned localfeatures flags
These flags may only be used in the init message:
| Bits | Name | Description | Link |
|---|---|---|---|
| 0/1 | option_data_loss_protect |
Requires or supports extra channel_reestablish fields |
BOLT #2 |
| 3 | initial_routing_sync |
Indicates that the sending node needs a complete routing information dump | BOLT #7 |
| 4/5 | option_upfront_shutdown_script |
Commits to a shutdown scriptpubkey when opening | BOLT #2 |
Assigned globalfeatures flags
There are currently no globalfeatures flags.
Requirements
The requirements for receiving specific bits are defined in the linked sections in the table above.
The requirements for feature bits that are not defined
above can be found in BOLT #1: The init Message.
Rationale
There's little point in insisting on an initial_routing_sync. You can't
tell if the remote node complies, and it has to know what the flag means as
it's defined in the initial spec. So, there's no even bit for this.
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