Universal Product Code

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Universal Product Code (UPC) is a barcode symbology (i.e., a specific type of barcode), that is widely used in Canada and the United States for tracking trade items in stores.The UPC encodes 12 decimal digits as SLLLLLLMRRRRRRE, where S (start) and E (end) are the bit pattern 101, M (middle) is the bit pattern 01010 (called guard bars), and each L (left) and R (right) are digits, each one represented by a seven-bit code. This is a total of 95 bits. The bit pattern for each numeral is designed to be as little like the others as possible, and to have no more than four consecutive 1s or 0s in order. Both are for reliability in scanning.