A barcode consists of two elements. In linear symbologies, the dark element is called Bar, and the white element is called Space. In two dimensional symbologies, both elements are referred as module - the dark (black) module and the light (white) module.

Most linear symbologies allow 1 or 2 widths. In the first scenario, the width of an element could be 2, 3 or 4 times of the width of the narrowest element. In the second scenario, two widths are defined, one for the wide elements and one for the narrow elements. The width of the wide element divided by the width of the narrow element is called NarrowToWideRatio. In both cases, the overall barcode length achievable depends on how small the width of the narrowest element can go. The width of the narrowest element is also referred as X dimension (sometimes abbreviated as “X Dim”). In Barcode DLL you can set the X dimension through property NarrowBarWidth.

The length of the X dimension is usually very small. The industry measures the X dimension in 1/1000 inch units, called mils. A mil equals to 1/1000 inch. Nowadays millimeters are also used in some cases. Due to the legacy that most barcodes have so far been produced by specialized barcode printers and most of those barcode printers have a low resolution at 203-dpi, the X dimension is often integral times of the pixel width on a 203-dpi printer - a typical requirement is 15 mils (the width of three printer pixels on a 203 dpi printer).

0 The smallest width that a barcode reader can distinguish is called scanner resolution. Today, most commercial scanners have a resolution around 10 mils, meaning that they won't be able to read the barcodes with X dimension at 5 mils. High resolution scanners can go as low as 3~5 mils.

Barcode DLL supports two measurement units: mils and high metric (1/1000 cm). The user can select whichever convenient to use. On the other side, although you can set whatever values you desire, you may not be able to achieve the accuracy because of the limitations of the device. You can not print on 1.5 pixels. If you plan to create barcodes on low-resolution devices, such as fax transmission, screen or thermal printers, refer to Chapter 6, Working with low-resolution devices.