Dymo LabelWriter 300,310,320,330 DLS 8 - Manual (Page 121)

automatically calculates the checksum for the 12th digit. This code requires
numeric information only.
UPC-E
Universal Product Code (UPC) version E is small in size and is commonly used for
small packages. The information encoded in the UPC-E barcode is identical to
information encoded in UPC-A barcodes, except that zeros are omitted from the
encoded number in order to reduce the number of digits from 12 to 6. This code
requires numeric information only. UPC-E can only be used for product UPC codes
(the product type character must be 0 or 1).
V
variable
When the label is printed the variable data on the label changes for each label
based on the source data. Source data can come from entries in the Address Book,
Smart Paste, Merge Print from Database, or DYMO Label Add-Ins.
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