Adjusting VTS Order
By default, when you first start DVD Studio Pro with a new project, you will notice that you have one default track asset and one default menu asset. These two assets share a single default Video Title Set, also known simply as a VTS.
Each time you add a track to the Outline tab, DVD Studio Pro essentially creates another Video Title Set on your behalf and places the additional track within that newly created VTS. So if you have just a single track asset in the Outline tab, you likely have just one VTS, called VTS1. As you add multiple tracks to your DVD project, you create VTS2, and VTS 3, and so on.
These Video Title Sets are later muxed into a collection of VOBs (Video Objects) which are stored in the VIDEO_TS folder of ...