Transcription: Once again, if you're used to database programming and foreign key primary key relationships, that's not what this serves for. It's nice that you can emulate some very similar things, but there are no entity constraints on the way that these elements interact. So for example, you could have an element who has an ID refs attribute, but that could point to any ID, not just a given element's ID, any ID that's declared within the document. So there's no constraint, there's no data integrity, there's no real relationship between the data. All it is is a pointer. This guy points to that guy. So use ...
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