I'm trying to integrate with Adobe InDesign and a plugin the is already created. Where do Instance and Document Id's come from? Are they meaningful or just a place holder to identify a file?
Are you talking about the Document IDs from the Media Management Schema (xmpMM:DocumentID)? If so, those are generated by the CS apps, usually on Save/Save As.. commands, and are designed really to be used by DAM systems.
See the XMP Specifcation on Page 43. It discusses the MM Schema.
Hope that helps.
Cheers,
-Andrew
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