Feature Trees are high-level models organizing features into feature groups, capturing the entire scope of a project into a single model. Features are listed into three separate levels of detail. The highest level features are shown on Level 1 (L1), mid-level features are shown on Level 2 (L2), and low-level features are shown on Level 3 (L3).
For more information:
Learn more about requirements models in our book Visual Models for Requirements.(See Chapter 6 for Feature Trees)
For more requirements templates see our BA resources.