This user interface (UI) reference chapter summary operational information about the UI and detailed overview of the primary controls on the top-of-screen Menu Bar and Icon Bar, and the right-side application Main Menu. The Main Menu is available for VectorStar VNAs. The Menu Bar provides drop-down menu interface to major instrument functions. The Icon Bar provides single-click access many instrument functions and is user-configurable to meet individual needs. The description of the Main Menu (MAIN) provides top level descriptions of each major function with links to detailed descriptions of menus and dialog boxes in subsequent chapters.