The FIX-3.5-18 part of Fix & Fasten is a standardized electronic protocol used for communicating between two parties to transfer trading-related information such as orders, quotes, and confirmations. It is based on the Financial Information Exchange (FIX) Protocol, which is an open protocol used in the financial industry to facilitate the exchange of real-time financial information. The FIX-3.5-18 version of FIX was introduced in 2002 and is currently the industry-standard version of FIX. This version of the protocol supports a wide range of trading activities, including options, futures, equity and foreign exchange (FX) trading. It also supports multiple trading strategies, such as algorithmic trading, which is a method of conducting trades that is based on mathematical rules and models.