This glossary defines the key terms used in FIX API trading and Forex execution. The definitions are short and plain, so traders, students, and anyone researching FIX API Terminal can quickly understand the vocabulary.
Quick Answer: FIX API trading has its own vocabulary — FIX protocol, FIX session, execution report, IOC, FOK, slippage, lot, notional value, and more. This page defines each term clearly, grouped into connectivity, order types and execution, trade size and cost, and automation.
FIX Protocol and Connectivity
- FIX protocol
- The Financial Information eXchange protocol, an open messaging standard for communicating trade-related information. It is used widely across professional and institutional markets.
- FIX API
- A connection to a broker that uses the FIX protocol, allowing a trader’s software to exchange orders, prices, and execution data directly with the broker’s FIX endpoint.
- FIX session
- The live connection established between a trader’s platform and a broker’s FIX server. All trading messages flow over this session.
- FIX message
- A single structured instruction or notification sent over a FIX session, such as a new order or an execution report.
- Execution report
- A FIX message returned by the broker that confirms how an order was handled — filled, partially filled, rejected, or cancelled, and at what price.
- Market data
- Price information, such as quotes and market depth, sent from the broker to the trader’s platform over the connection.
- FIX API broker
- A broker that provides account connectivity through the FIX protocol. A FIX API broker is required for live FIX API trading.
- FIX API credentials
- The connection details a broker issues for a FIX API account, used by the platform to establish the FIX session.
- Liquidity provider
- A bank or non-bank institution that supplies tradable prices. Brokers source liquidity from one or more providers.
- STP (Straight-Through Processing)
- An execution model in which orders are passed through to liquidity without manual dealer intervention.
- Direct market access (DMA)
- A model in which a trader connects more directly to market liquidity, rather than only through a broker’s standard retail platform layer.
- Latency
- The time delay between sending an order and its execution, and between execution and confirmation. Lower latency matters most for timing-sensitive strategies.
Order Types and Execution
- Market order
- An order that executes immediately at the best available price. It prioritises certainty of execution over price and can be exposed to slippage.
- Limit order
- An order that executes only at a specified price or better. It controls price but may not fill if the market never reaches the limit.
- Stop order
- An order that becomes a market order once the market reaches a trigger price. Commonly used for stop-loss protection and breakout entries.
- Stop-limit order
- An order that becomes a limit order once a trigger price is reached, combining a trigger with control over the fill price.
- IOC (Immediate or Cancel)
- An execution condition: fill as much of the order as possible immediately at the price or better, and cancel the rest. Partial fills are accepted.
- FOK (Fill or Kill)
- An execution condition: fill the whole order immediately at the price or better, or cancel it entirely. Partial fills are not accepted.
- Time in force
- How long an order stays active, for example Day (expires at end of day) or GTC, Good-Till-Cancelled.
- Slippage
- The difference between the price a trader expected and the price at which an order actually executed.
- Round turn
- A complete trade cycle — opening and then closing a position. Trading fees are often quoted per round turn.
Trade Size and Cost
- Lot
- A standardized unit of trade size. In Forex, lot size is measured in units of the base currency.
- Standard, mini, and micro lot
- A standard lot is 100,000 units of base currency, a mini lot is 10,000 units, and a micro lot is 1,000 units.
- Notional value
- The full value of a position — contract size multiplied by price multiplied by the number of lots — not the price of a single unit.
- Pip
- A standard small unit of price movement in a currency pair. Pip value scales with lot size.
- Spread
- The difference between the price at which a trader can buy and the price at which they can sell. Part of it is the market spread and part can be a broker markup.
Automation
- MQL robot
- An automated trading strategy written in the MQL language. Also called an Expert Advisor. In FIX API Terminal, the robot source code file, such as *.mq4, is required to run a strategy.
- Manual, automated, and semi-automatic trading
- Manual trading means placing each order by hand; automated trading means a robot executes a strategy; semi-automatic trading combines the two, with the trader supervising an automated strategy.
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