Sun Microsystems StorageTek StreamLine SL8500, System Assurance Manual

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166 SL8500: Systems Assurance Guide • July 2011 E24254-01
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Barcode Labels
The labels used for the tape drives and libraries are based on the Code 39
barcode standard. This standard uses discrete barcodes, which means that a
fixed pattern of bars represents a single character.
Each character is made up of nine bars— five black bars and four white bars—
three of which are wider than the others. This is the reason for the name Code
39 and why some people refer to it as the 3 of 9 Code.
Figure 54. Barcode Label Examples
For example: This barcode represents the letter A, using
• Six narrow bars and three wide bars
• Two wide black bars and one wide white bar
Inter-character Gap
When multiple characters are arranged together as a label or
volume serial number (VOLSER), a single, narrow white bar is
placed between the individual character barcodes.
This is called the Inter-character Gap.
The Code 39 standard supports 36 unique alpha-numeric
characters—the letters A through Z and the numbers

0 through 9—for use in making customer labels.

Note that no lower case letters are used.
This standard also supports seven special characters

( - . $ / + % * ), which are not part of the customer label.
Delimiter
For the decode algorithms to function properly, delimiters or
start and stop characters are needed to bind the actual
barcode label characters together.
One of the most common characters to use for a delimiter is
the asterisk (*), one of the seven special characters. The
asterisk should never be used in a barcode as part of the
customer-defined characters.
Barcode algorithms only decode the characters between the asterisks; they ignore characters outside
the asterisks. For example:
Actual Barcode Label After Decoding Comments
*ABC123* ABC123 Good label
*ABC*23* ABC Misplaced stop character
ABC*23* 23 Misplaced start character
*ABC5678 Unreadable No stop character detected