This
character is used to instruct the scanner in which direction the
barcode should be read. For the data characters, each consists of 5 bars and 4 spaces; three of these elements are wide and
the other six narrow. The reason for choosing Code 39 as the
format to be used, as opposed to the other available types, was
because it was found that two characters in this system have
“correlated” barcodes (Fig. 2b).