The performance of B-level bar code is not as good as that of A-level bar code when reading, and it is suitable for situations where only one line is scanned but repeated scanning is allowed.
Class C barcodes may need more repeated scanning, and it is usually necessary to use equipment with multiple scanning lines to obtain better reading results.
Some devices may not be able to read class D barcodes. In order to get a good reading effect, it is necessary to use a device that can be scanned repeatedly and has multiple scanning lines. Class F barcode is unqualified and cannot be used.
Usually, American standard testing methods are used to test five quality grades "A" to "F", with "A" being the best, "D" being the worst and "F" being unqualified.
Extended data
Uniform product code:
It can only represent numbers. There are five versions: A, B, C, D and E, with version A- 12 and version E-7. The last bit is the parity bit. The size is 1.5 "high 1" and the background is clear. Mainly used in the United States and Canada, used in industry, medicine, warehousing and other departments.
When UPC is decoded into twelve bits, it is defined as follows: the first bit = digital identification (established by UCC (Unified Coding Committee)). Second-sixth digit = manufacturer's identification number (including the first digit) 7- 1 1 = unique manufacturer's product code 12 digits = parity bit (for error).
Code 3:
Can represent letters, numbers and other symbols ***43 characters: A-Z, 0-9,-. $/+%.The length of the pacing bar code can be changed. Usually "*" is used as the starting and ending symbols. The code density is 3-9.4 characters/inch, and the blank area is 10 times of the narrow strip, which is used for checking codes.
Code 128:
Represents high-density data, with variable string length and symbols containing check codes. There are three different versions: A, B, and C can use 128 characters in the three string sets of A, B, or C for industry, warehouse, retail, and wholesale.
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It can only represent numbers 0 -9, variable length and continuous bar code. All bars and spaces represent codes. The first number begins with a bar, and the second number consists of spaces. The blank area is 10 times wider than the narrow strip. Used in commodity wholesale, warehouse, airport, production/packaging identification and industry. Bar codes have high recognition rate, can be used for reliable scanning of fixed scanners, and have the highest density among all one-dimensional bar codes.
References:
Baidu encyclopedia-barcode