Please help to identify the LEGO Plastic Bags # (2,4-319g7,5-419g7,7-219g7) I used QR code reader and it gives me a digits of 6172090. Unfortunately I could not find any information. I bought this items only in LEGO plastic bags with no other info. from a recycle store. Thank you!
Everything Lego does carries an SKU (Stock Keeping Unit).
If you look at most recent instructions, you have a list of parts with 7 digits numbers, that's the part SKU.
Similarly, each set has an SKU (labeled as "item number" next to the EAN / UPC barcode on the box), the box itself has an SKU (written smaller, generally) each instruction / pamphlet has one or more SKU (depending on version) and thus each bag in the box has it's own.
Also recent boxes have, next to the product barcode, a small white box, which appears to contain a lot numbers and production serial numbers which is readable as a datamatrix).