I am using the Automation interface to view lideID's for an application that
reassembles PPT slides.  I have noticed that the slide id is generally a
small integer and that while they appear to be unique within a presentation,
if one deletes a slide and then adds a new one there appears to be a chance
that an old slide id will be reused.

Can someone let me know when exactly slide id's are generated (for example
my experiments seemed to show that if one deleted a slide and added one, it
gave the same results as the other way around if there was not a save in
between which suggests that ids may be added at save time) and via what
algorithm (even approximately) and whether there is some combination of
attributes (possibly other than the iD) that will be unique?  I am using
Office 2003 although the application shoud also work with 2007.

Thanks,

Lyman