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From: Luke Dashjr <luke@dashjr.org>
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Date: Mon, 19 Jun 2017 19:26:22 +0000
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Subject: [bitcoin-dev] BIP148 temporary service bit (1 << 27)
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To ease the transition to BIP148 and to minimise risks in the event miners 
choose to perform a chain split attack, at least Bitcoin Knots will be using 
the temporary service bit (1 << 27) to indicate BIP148 support.

Once the transition is complete, this will no longer be necessary, and the bit 
will be (manually) returned for reuse.

I encourage other software implementing BIP148 (both full and light nodes) to 
set and use this service bit to avoid network partitioning risks.

Luke