A bin is a storage area in a wine cellar. With each successive harvest, wines were allocated the same bin year after year. With time the bin number became associated with the wine - the Shiraz was stored in bin 50, the Chardonnay in bin 65, for example. It is unsurprising that the bin numbers have now become brand names depicting a style of wine, and have nothing to do with the origin of the grapes or where the wine has been stored!