How to use .forItems() on a repeater?

@bwprado I’m trying to figure out what the highlighted arguments represent here:

repetitor.forItems([’ item1 ', ’ item4 '], ($item, itemData, index)= > { } )

Initially, I thought those were the IDs of the repeater’s items, but we have acknowledged that it’s not possible. So I was was wondering if the highlighted values represent the _id property or something else?

In case those represent the [’ item1 ', ’ item4 '] represent the _id property, it would be nice to rename them so that they can easily be associated with the item they’re referring to. For instance if the items is a list of brands, I’d like the _id to be something like ’ itemBrands '.