unique identifiers in word .docx documents?

Are there any decent UID's in the xml metadata embedded in .docx documents? I can't spot any obvious ones but I dont do this too often.

I've used 'creator' before when it was quite specific ('Rupert Q Specialname') - but I've got a bunch of documents that I know were made by the same person - and I need an easy way of spotting future ones also made by the same person.

Unfortunately the 'creator' on these ones is just …

computerforensics documents docx embedded future metadata word xml