UPC-A EAN13 and Bookland require checksum digit to be appended at rear end of data. If you use Barcodesoft UPCA EAN13 fonts to print bar code please use our Encoder to calculate checksum for you. You can also find source code in VBA and C language of UPC-A EAN13 checksum calculation in the package. There are 6 fonts contained in the package as listed below marked by different trailing aspect ratio indicators. Barcodesoft UPCA EAN13 barcode fonts vary in aspect ratios. Barcodesoft UPCA EAN13 barcode fonts are available in true type PostScript and PCL formats and can be embedded into Adobe PDF files. There is also a sample in the package. You will find how easy it is to integrate bar coded data with your own application. Barcodesoft UPC EAN Packages include a 30-day money back guarantee. If you are dissatisfied with the product for any reason you will receive a full refund within 30 days.