Once you have a real VMG menu then Title button links to the first VMG Menu (The TITLE menu, hence its name). If you don't have any VMG menus then Title button can be routed to a VTS root menu or even a Movie. Please understand Title button is different than Menu button on DVD remote - Menu button will always link to currently played VTS ROOT menu regardless of any VMG menu or Title button links. The Title button is sometimes called also a Digest on some remotes.
