I'm sure this is documented somewhere, but...
In the Labs DB replicas, I see the wbc_entity_usage table. I assume that
logs the Wikidata entities used for a particlar page.
* What is eu_aspect? What do "L.de"/O/S/T/X mean?
* Is one of these the item ID of the page (as opposed to "arbitary use")?
If so, which one? If not, how could I find this information on the replicas?