- Started in `ProcessNewBlock`, `main.cpp:4258`
    - Calls `CheckBlock`, defined at  https://github.com/zcash/zcash/blob/ab2b7c0969391d8a57d90d008665da02f3f618e7/src/main.cpp#L3930
        - Calls `CheckBlockHeader` https://github.com/zcash/zcash/blob/ab2b7c0969391d8a57d90d008665da02f3f618e7/src/main.cpp#L3900
            - checks that the block version is not too old
                - this requires no information
            - checks that the equihash solution is valid
                - https://github.com/zcash/zcash/blob/ab2b7c0969391d8a57d90d008665da02f3f618e7/src/pow.cpp#L96
                - requires no information except `n`, `k` params
            - checks that the proof of work parameters are valid
                - requires the current proof of work amount `params.powLimit`
        - Checks the Merkle root
        - Checks size limits
        - Checks that the first transaction is coinbase, and the rest are not
        - Calls `CheckTransaction` for each transaction
        - Sum up "LegacySigOps" for each transaction and check that it's less than some maximum
    - Acquires a lock, then calls `MarkBlockAsReceived` (networking?) and then calls `AcceptBlock`
        - 
- ContextualCheckBlock