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The overview can be found in the Data Products Definition Document. (note that this is temporarily out of date; should be updated by ~August 2020).
The detailed schema is at https://docs.google.com/spreadsheets/d/1E0rTlvuJC0CvpLNsuWLK0x70uhpZww4v6GB5QkiQr-Q/edit#gid=1982710437
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