One-dimensional bar codes
46
Notes on ISBN, ISBN+5:
ISBN bar codes are EAN-13 symbols that encode the first nine digits of an ISBN (the checksum digit is not
encoded), prefaced by a special Bookland country code (978). The complete 10-digit ISBN is usually printed in
its human-readable format along with the symbol; this is in addition to the text that may appear showing the 13
digits actually encoded by the EAN-13 symbol. The bar code descriptor for ISBN, therefore, contains two sets
of fields for specifying the placement, typeface, and style of these two separate text strings.
The data for an ISBN symbol should consist of a 10-digit ISBN, optionally followed by a five-digit add-on code.
If a five-digit add-on code appears in the data, then an EAN-13+5 symbol is generated, with the add-on code
encoded in the +5 section of the symbol. The last digit of an ISBN, the checksum digit, may be an “X” (ASCII
88). Also, to enhance readability, “-” characters (ASCII 45) may appear anywhere in the data; they are ignored.
The “-” characters in the ISBN text printed with the symbol are inserted by a hyphenation algorithm, not based
on where they appear in the data.
Since the checksum digit is not actually encoded in the symbol, it is required in the data only for the purpose of
including it in the ISBN text printed with the symbol. The ISBN checksum digit is not verified or replaced by a
calculation in the Forms and Bar Code Card.
An invalid length (anything other than 10 or 15 digits), or an invalid character (anything other than a digit or a
“-”, except for an “X” in the tenth digit position) in the data produces an error message. Cursor positioning is
handled the same as for other one-dimensional symbologies.
If the Units bytes 5 or 8 are changed from their default values, then the Bar Height and Bar/Space Width
parameters assume new dimensions, based on the new units. In other words, the parameters are in “units”,
and if the “units” measurements change, so does the physical printed bar code.
If any of the parameters are set to zero, then the default value assigned in the table is assumed.
25 ISBN Text
Location
0–5 (dec)
00–05 (hex)
5 (dec)
05 (hex)
Specifies location of ISBN text.
0 = Use default value
1 = Do not print
4 = Below symbol
5 = Above symbol
26 – 31 Reserved — — —
Byte Field name Range
Default
value
Description
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General
Weight and Dimensions
