Let’s talk through these three principles:

First the Postings API is a unified method for all financial movements. We expose a single API from

Vault that can act on any financial movement. These financial movements would be between a single

account’s balances, or between two accounts in Vault. You can also represent the movement of funds

external to the Vault system using postings.

External Integrations will use the Postings API, for example to make postings in journeys such as Card

Payments and Inter-Bank Transfers. Vault Services will use the Postings API to complete on-Vault

postings, such as Accrual of Interest of Accrual of typical Fees on an account. This enables flexible

and unified management of the financial state of accounts on Vault.

Next, Consistency of Financial State. What does this principle mean?

1. Postings are immutable, meaning they cannot be edited once they have been committed to

our append only postings ledger. The benefit of this is that you know that the postings you

see in the ledger are the original, and will never be edited or removed.

2. Postings are the lowest level movement of funds. Postings are not Customer Facing

transactions - a single Customer Transaction or Payment can be made up of many postings.

3. Balances in Vault are always computed according to the postings within the ledger, our single

source of truth for movement of funds.

4. The Postings API guarantees consistency through following the double entry book keeping

model and ensures all requests follow this principle. We’ll refresh Double Entry Book Keeping

in the Vault context for you later in this session.

5. The ability to model complex financial processes. The Postings API provides a number of

Posting Types, such as Authorisation and Settlements. We’ll walk you through each of these

types later in the session. These types of postings are used to model complex financial

processes such as Card Payments, and the types of postings allow you to record a statement

of intent with your postings (for example, I would like to Authorise $100 from my Customer’s

account).