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When a new block is added, that block may have many transactions. Each block has automatically generated metadata, as does each transaction. You can also add custom metadata.


numberBlock number for this block.
hashHash for current block. Not included in block hash (can't include itself!).
prevHashPrevious block's hash
transactionsReference to transactions included in this block (_tx).
ledgersReference to transactor auth identities that signed this block. Not included in block hash.
instantInstant this block was created, per the transactor.
sigsList of transactor signatures that signed this block (signature of _block/hash). Not included in block hash.


tempidsTempid JSON map for this transaction.
sigSignature of original JSON transaction command.
txOriginal JSON transaction command.
docOptional docstring for the transaction.
altIdAlternative Unique ID for the transaction that the user can supply. Transaction will throw if not unique.
nonceA nonce that helps ensure identical transactions have unique txids, and also can be used for logic within smart functions (not yet implemented). Note this nonce does not enforce uniqueness, use _tx/altId if uniqueness must be enforced.
authorityIf this transaction utilized an authority, reference to it.
authReference to the auth id for this transaction.