Top-Level Groups are used for many organizational and functional purposes in WebWorks Reverb 2.0. Once a help set is generated as a WebWorks Reverb 2.0 Output, Top-Level Groups are converted into a hierarchical structure to form the Parcels that make up the Table of Contents, and the structure in the file system. These Parcels can then be selected by the user when using Scoped Search to filter search results, and also using the URL method to filter a help set into a subset that contains a specific section of the entire set.