Taylor Swift, who holds the No. 1 album for a second time with “Folklore,” maybe one of the last stars to benefit from Billboard’s so-called bundling rule, which lets artists sell albums with merchandise or concert tickets.

Swift is also the last to gain an advantage from a lesser-known chart rule, one that is a bit of a brain-twister: the bundling of a physical album with a digital one.

Billboard has long tried to reconcile the delays that can happen when a fan orders a physical copy of an album, like a vinyl LP, from an artist’s website.

With release cycles moving faster than ever these days, records and CDs are sometimes not ready to ship when a new title starts streaming; in the case of vinyl, backlogs of weeks or even months are common.

So artists often combine the sale of a physical album and a digital version and send fans the digital one while they wait.