FIX-3.5-8 is a subset of the Financial Information Exchange (FIX) protocol, developed and maintained by the FIX Protocol organization, Inc. (formerly known as FIX International). The protocol is a protocol for real-time, secure communication of financial data such as orders, quotes, trades, and other market data. It is used primarily by brokers, exchanges/market makers and institutional investors. The version 3.5-8 of this protocol is the most commonly used version and is used in most equities and derivatives trading applications. It provides application-level message flow and data integrity to ensure secure and accurate communication between two parties over a TCP/IP connection. This version of FIX is based on a set of field tags and associated values, which allow the sending and receiving of messages over a connection.