It's basically date based. Factors involved are starting date, ending date and current date. Other fields are present to aid the "reader". Do YOU know what products_id 189 is? Maybe as one that manages the ZC data all the time you might, but someone that works in "the store" doing inventory or selling an item, more than likely they know it by it's name or description.

At any rate, the code works like this: if the available date for the featured item is less than the current date and the current date is less than the end/expire date, then the product is turned "on" during import with ZC taking over the remaining on/off controls, if the current date is before the start date or after the end date then as written EP4 will turn off the featured item. That said, the test probably should be if it is after the end date but the end date isn't "empty" (0001-01-01) then turn it off, after all if someone wants a product to *always* be featured after some point, then that would seem like the date to use, but probably also need to look at how ZC accomplishes this before making that change.

Anyways, that's a brief description of the operation. This is not "product type" specific meaning that using bookx or not, the core EP4 code works as described above, though it does look like it could use some minor improvements in this area. (More for Version 4.0.35 :) )