There is a BOM!
BOM (Build of Materials) references every part that goes into building a specific part. If you were building a Video Card your BOM would include each component right down to the resistors and PCB used in the product. Normally a BOM is only component specific. A BOM might say six layer PSB (Green) or 100 .1 Ohm resistors but it would not go so far as to state the Lot Number, revision number or anything else.  If you take a typical stick of memory you might notice that the chips do not always match for lot number.  The same can be said for building any component. Companies do not have time to match lot numbers as they build product. In fact most do not even try. They take parts from stock as they are put in. Oddly enough, it is only by chance that you get parts from the same Lot. This happens because when Lots are manufacturer they are packaged for shipment around the same time so these components end up going to the same places.  As Lots are usually in the hundreds of thousands there is a good chance that you may get the same Lot parts in a single product.

To a consumer buying a dual or triple channel kit of memory you this means that your chance of getting parts with different Lot components it fairly slim. To the Enterprise customer who buys 16, 32, 48, or more sticks of memory in a single purchase the likelihood goes up dramatically.