Auto fillable Fields

Some fields can be automatically filled in before a transaction is signed. Auto-filling values requires an active connection to the XRP Ledger to get the latest state, so it cannot be done offline. ripple-lib can automatically provide the following values:

• Fee - Automatically fill in the Transaction Cost based on the network.
• Sequence - Automatically use the next sequence number for the account sending the transaction.
• LastLedgerSequence aka maxLedgerVersion - Automatically use the current ledger version plus 3.
• Paths - This field of the Payment transaction type can also be automatically filled in.

For a production system, do not leave these fields to be filled automatically, unless you have carefully considered the consequences. If transaction costs become high due to a temporary spike in network load, you may want to wait for the cost to decrease before sending some transactions, instead of paying the temporarily-high cost.