Segwit2x: What you need to know
Jimmy Song

I believe that “Signaling at bit 1 or bit 4 are accepted.” is wrong.

Only bit 4 signalling counts towards the 80% threshold needed to activate Segwit2X’s orphaning of blocks that do not signal bit 1.

Explanation of bit 4 signalling process here

Code that controls the activation (bit 4 at 80%) here: