MSI Code is a numeric, continuous code. Each character consists of four bits, using a straight binary encodation. Each bit is encoded in the following way: if the bit is a 1, the pattern to be used is a wide bar followed by a narrow space. If the bit is to be a 0, the pattern is a narrow bar followed by a wide space.
To learn how to add an MSI barcode in eFORMz, check out this video: