invalid command format

Open the DVD in PgcEdit. It will highlight invalid commands for you. Then edit the command, save the DVD and reopen it in DVD remake Pro.

any chance of you expanding on that? Been to pgcedit manual, but to say its all greek would be an understatement.

First of all - if you have not ripped your DVD to HDD, do it. This way you can edit it before using DVD Remake Pro. Run PgcEdit and open your DVD in it - this should not make any trouble. Then, on the left pane, navigate to VTSM 1, PGC 4. Just look for something like "VTSM 1, LU1 (en), 4", and click it. (I do not know DVDRemake, so the message you're getting may very well point to VTST 1, PGC 4 (ie. in the title domain, not in the menu domain)). On the right pane you will see commands of the PGC. See, if command #37 is highlighted as erroneous. Double-clicking the command allows you to edit it. Until you provide more details of the "invalid" or "not allowed" command, I cannot do more, I'm afraid.

six pre commands are listed for VMGM 1/4, the fifth highlighted in yellow. It says" (JUMPSS) Jump to VTSM 20, Root Menu (TTN 1)". VTSM 1/4 has no pre, post or cell commands listed. Is this an error? what is the fix?

Light yellow? Or orange? If light yellow, then the line is the target of a GOTO command in the same section ("pre commands"). If it is orange, the command is invalid in that it points to nonexisting VTS (do you have VTSM 20 in your DVD?). Did you look into VTSM 1 or VTST 1? The error message you provided in the first post mentions pre command 37 in PGC 4, and you've just said there are only six there...

The LinkTailPGC is allowed only in cell commands and in buttons. Unfortunately, without full analysis of your DVD, I cannot help you more (i.e. you'd have to check if gprm(0) ever gets values 25-28, and if not - you could safely delete these four invalid commands). How many POST commands are in this PGC? Is there a "LinkCN" among them? Is this PGC a standalone title (does it have a, say, "Title 6" in the left pane) or a continuation of the previous one?

I changed the four in error to read as the previous 36, but this resulted in a new error that they were referring to programs 25 thru 29 when only 24 programs exist. So I decided to delete the errors. No new errors now. Will test this and report back. Thanks for the help.

Make sure you use an up to date ripper. If you have, there is a possibility that these commands are skipped anyway (this is often seen in advanced protection systems) and you have nothing to worry about. Regards

deleted, it was a wrong suggestion (DVDRemake actually doesn't allow for the LinkTailPGC in pre-commands)

P.S. You could try to understand what those DVD authors meant by addressing TailPGC ('post-command' list for that very PGC, could you post it?) and edit the pre-commands into legal ones.