additional document for BIP32
Check https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#serialization-format
((sequence &amp; 0x80000000)==0) means it's not a hardened key. The key is hardened (public key derivation not possible) for child keys with index higher then 0x80000000 (== 2147483648 == 2^31).
From the BIP
4 byte: version bytes (mainnet: 0x0488B21E public, 0x0488ADE4 private; testnet: 0x043587CF public, 0x04358394 private)
1 byte: depth: 0x00 for master nodes, 0x01 for level-1 derived keys, ....
4 bytes: the fingerprint of the parent's key (0x00000000 if master key)
4 bytes: child number. This is ser32(i) for i in xi = xpar/i, with xi the key being serialized. (0x00000000 if master key)
32 bytes: the chain code
33 bytes: the public key or private key data (serP(K) for public keys, 0x00 || ser256(k) for private keys)