4. T for Track bar. The DAFT text strings when presented in the Royal Mail 4-state font form the Royal Mail 4-state Mailmark barcode. Figure 36 shows a Full bar followed by a Descender bar, an Ascender bar and a Track bar. All systems that are required to read and extract data from Barcode C and L Mailmark shall have a configurable file that can contain up to 100 different 2 character strings to identify different data fields within the code. The configurable file shall for each of the Barcode C/L Mailmark defined by the 2 character string: • assign the precedence of each Barcode C/L Mailmark string where more than one Barcode C/L Mailmark exists on a Mailing Item; • set the threshold limit for the amount of error correction by the ECC algorithm that is allowed before rejecting the code read; The representation of the 2 character string within the configuration file shall comprise of characters 0 – 9 only. No wild cards will be used. 14.5 Optical specification for all Royal Mail 4-state barcode Mailmark The Mailmark barcode must be printed so that it contrasts with the background, typically black bars on a white background, and the print quality shall be consistent throughout the code. The optical characteristics of the printed Mailmark barcode characters can vary substantially, depending on the varied print processes used to produce them, and the quality of the substrate onto which they are printed. Please make sure that the reflectance and print quality characteristics are maintained within acceptable limits, to ensure the reading process is reliable. 14.6 Print Contrast Ratio (PCR) for all Royal Mail 4-state Mailmark barcodes The PCR is an indication of how well the printed Mailmark barcode on the Mailing Item stands out from the background. For Mailmark barcode mail this must be a minimum of 40%. Positive Contrast or Inverse Printing (Barcode lighter than the Background) is not permitted. 14.7 Symbology, dimensions and tolerances measurement for the Royal Mail 4-state Mailmark barcode When Mailmark barcodes are magnified, their edges may not always be clearly defined, making accurate measurement more difficult. In order to ensure that measurements are within required specifications, it is necessary to define the edges between each light and dark element of the Barcode. The edge of a bar is defined as: “the position where the apparent reflectance is exactly halfway between the minimum and maximum reflectance values of the adjacent bar and space, when viewed using a circular sample aperture of less than 0.6X, where X is defined as the nominal width of the bars in the code”
the 2D data matrix Mailmark barcode is differentiated from other Data Matrix symbols by a defined string of 6 characters in the first part of the data within the code. Each of the Royal Mail products that use the 2D data matrix Mailmark barcode has the following data strings in the first part of the data content: - UPU identifier – 1 Characters (J); - Royal Mail identifier assigned by the UPU – 3 Characters (e.g. GBA, or GB
1. D for Descender bar; 2. A for Ascender bar; 3. F for Full bar; and
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