Domains; Which One Is It In and When Does It Change

[farmer dan]

I understand that different commands must be used to get out of one domain and go to another--JumpSS, CallSS, for example. What I'm struggling with is the concept of which domain I am in at any one time and when those domains change. For example, A DVD does executes the following sequence: 1. enters at the First Play PGC domain (First Play PGC domain)
2. JumpSS to PGC-1 (goes to VGM Menu domain)
3. JumpVTSM to a Root Menu (goes to VTSM Menu domain)
4. LinkPGCN PGC-3:Menu_3 (goes to VTSM Menu domain)
5. JumpTT (goes to VTS Title domain)
I have put the domains that I think are current in red. Is this assessment correct?

Please consider the following extracts from MPUCODER's Website:1. This CallSS VMGM command calls VMG menu type "K" (byte 5 lower nibble) from a title. The RSM command will return to the point in playback where the CallSS was issued unless "RR" (byte 4) is used to specify a different resume cell.
2. This JumpSS VMGM command jumps to VMG PGC "NNNN" (bytes 2&3) from a menu (system space)
Do the CallSS type commands act like the basic command "CALL Subroutine (xyz)"--" which inserts a certain set of lines into the running program at Point A and the program continues to run at the next sequential step, Point B? If this is the case, then, using a CallSS from a Title leaves the navigation in the Title of TitleSet domain. (Unless there is a Jump somewhere in the call. Is this right?

Do the Jump type commands directly transfer to other system spaces (I hope this is another word for domain)?

Here's another statement on which I would like opinion. If this is the navigation,1. from a VMG Menu
2. I call a Titleset Root Menu from a pre-command
3. which jumps to a title from a pre-command
4. which calls the same VGM PGC from a post command,I have gone from the VMG Menu domain, to the Titleset Menu Domain, to the Titleset Title Domain back to the VMG Menu domain. In all this the only PGC that actually plays is the Title. (Too bad there's no smilie with a sweaty face :D) Is this correct?

I've encountered a problem in which at least one of the following statements is true:1. Navigation Problem
2. burning problem
3. player problemI'm tyring to eliminate the navigation alternative and wanted to bolster my conceptual understanding of the commands required to get from one place to another in the DVD. Before I ask for help, I want to make sure I can ask the question I need to.

Thanks.

[mpucoder]

There is a graphic (http://www.mpucoder.com/dvd/vmi-jmp.html) showing all the moves from one domain to another.
In short, You jump from one domain to another with the exception of leaving the title domain. From the title domain you use CallSS, and it remembers where you were in the title PGC, but you still change domains.
Link never changes domain, it moves about in the same domain. Your example above with LinkPGCN would only be correct if already in the VTSM domain.
Domains and spaces are not the same. There are 4 domains, First Play (FP_DOM), VMG menu (VMGM_DOM), VTS menu (VTSM_DOM), and VTS title (TT_DOM). The 4 spaces overlap and are a concept for knowing when certain things are allowed, they are:
System Space - FP_DOM, + VMGM_DOM + VTSM_DOM, ie everything except titles.
Menu Space - VMGM_DOM + VTSM_DOM, ie all menues
VMG Space - FP_DOM + VMGM_DOM, ie intro and title menu
VTS Space - VTSM_DOM + TT_DOM, the menues and titles of one titleset

In the last example you are using pre-commands. These will execute before anything is "played", and if they transfer control to another PGC that is the end of the current PGC's execution. If you want to play some video before moving to the next menu or title use post-commands.

[farmer dan]

Thanks, MPUCODER

Let me take this opportunity to thank you for constructing your web site. It has been a great resource for me as I learn this stuff. I have referred others to it so that they also might learn.

Your answer "hit the nail on the head" for me. In the mental picture I had of domains the boudaries between them were pixellated :D. They are much sharper now. Thanks again.