Choose the Browse button to the right of the unit of measure Pack. The Bar Codes window opens. Multiple bar codes can be set up for an item. Choose a unit of measure on the left and you can see the bar codes for this item and unit of measure. One bar code for each unit can be set as the default. Defaults appear in bold. Pack is set as the default UoM and the first bar code is set as its default, therefore this bar code appears on the header of the item.