This blog post by Betsy Stockdale explains how to use the Feature Tree model to discover missing requirements.
The Feature Tree is defined as “RML (Requirements Modeling Language) objectives model that shows the organization of the features in logical groups, displaying the full scope of a solution in a single page. There are three possible levels of features that might be useful for organizing the requirements: Level 1 (L1), Level 2 (L2), and Level 3 (L3). Below L3 are individual requirements themselves. Feature diagrams show all of the features at once, giving a quick view of the solution’s breadth of functionality.”
The Feature Tree is indeed a powerful visual model that allows to visualize the scope of a project and to discover areas where requirements can be missing.
Read the complete blog post on http://requirements.seilevel.com/blog/2013/11/find-missing-requirements-with-the-feature-tree.html