The Decision Table is an RML systems model that helps you to analyze all the permutations of complex logic in a comprehensive way. They are used to answer the question “Under what conditions will this outcome occur?” or “Given these conditions, what outcome should I choose?” The format of the model allows you to easily ensure that all possible conditions are being checked and acted upon properly and are used if there is no specific order to evaluating the decisions. If the decisions need to be made in any kind of order, a Decision Tree should be used instead.

As shown above and below, a Decision Table is represented as a grid. The top row contains labels for the business rules and the first column contains all of the possible conditions and outcomes. Each of the remaining columns in the grid represent the valid outcomes for the specified decision. The table provides a compact format for a large amount of information, making complex decisions appear orderly and complete.

For more requirements templates, visit Requirements Modeling Language.

Learn more about requirements models in our book Visual Models for Software Requirements (Microsoft Press, 2012) Joy Beatty and Anthony Chen. (See Chapter 16 for Decision Tables)