when can I set a substack's properties?

[Charles Hartman]

I'm not clear about when a substack "exists." I want to set some  
custom properties in a substack from a script in the main stack, and  
it would be a lot handier if I could do it before issuing the "open"  
command for the substack. It seems to work OK during my development  
cycle in the IDE. But will it work (in a stack being run under the  
Dreamcard Player) the first time out of the box? Or do I have to  
issue an "open" command before Rev will know the substack exists, and  
where to put stuff in it?

The substack is part of the stack file, so is it true that Rev knows  
all about it, and properties (custom or built-in) can be set before  
it's opened? The IDE's own evidence is kind of mixed: the Application  
Browser knows the substack while it's closed, but the Inspector doesn't.

Charles Hartman