Triple entry bookkeeping is the holy grail of all accountancy theories. It is a proposed alternative to double entry bookkeeping. Currently to maintain accounts, both parties need to maintain a ledger, with no way of reconciliation without a "trusted" third party.
A simple example as showed below.
Triple entry accounting: Rather than keeping and adjusting records of the same transactions in a privately managed, independent database, both parties are also recorded in a shared book. This, and the ability to record transactions in real time, enables the Blockchain to end the traditional invoices, documents, contracts and payment processes of large businesses and industries. Triple entry accounting as evolved in Ian Grigg’s paper in 2005. Grigg proposed a third entry by cryptographically sealing the transactions between counterparties. Grigg’s concept focuses on the digitally signed receipt which could provide strong audit trail evidence leading to more reliable financial data.