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They are transactions of type "transfer" recorded on the Hive blockchain between Hive accounts. Exchanges need to have a Hive account (eg. @deepcrypto8, @bittrex, @upbitsteem) to receive Hive deposits and to facilitate withdrawals.

Thanks, that clears it up for me. I thought so, but wasn't sure! :)

Yes it is transfers to exchanges hive wallets and back

Thanks! Makes sense now.
Great work, very useful :)