Originally Posted by francophile

If the "Y104 28075" is stamped under the bottom bracket shell and you didn't buy the bike brand new in 1981, I suspect this barcode sticker is from to one of the stores the bike passed thru during its lifetime, or it was possibly applied to the bike during a move or in freight, or as added by one of its owners.

To my knowledge, I don't think Peugeot was using barcodes on its bikes until after the turn of the century.