what do these values in chainparams.cpp do? what do these values in chainparams.cpp do?

consensus.nMajorityEnforceBlockUpgrade = 2;
consensus.nMajorityRejectBlockOutdated = 3;
consensus.nMajorityWindow = 3;


and how do I find them in the existing blockchain when upgrading end for new?

first time I think it's when start diff grow up, but now think it's wrong.
what do these values in chainparams.cpp do?


If nMajorityEnforceBlockUpgrade out of the last nMajorityWindow blocks have signaled support for a softfork, enforce the softfork's rules on the blocks that have signaled support. 

If nMajorityRejectBlockOutdated out of the last nMajorityWindow blocks have signaled support for a softfork, mark blocks with an old version as invalid.

These are for BIP34 style softforks.