Code 3 of 9 (also known as Code 39) is an alphanumeric barcode that can store decimal numbers, uppercase characters, and some punctuation characters: - (dash), . (period), $ (dollar sign), / (slash), % (percent sign), and + (plus). There is also an asterisk character *, used exclusively as a start/stop character.

Extended Code 39 is a variation of the basic barcode that encodes the full ASCII character set (128 symbols) by pairs of Code 39 characters.

The generator supports all features of these barcodes, including checksum generation. Symbols of Extended Code 39 should be passed in URL-encoded form.

Besides parameters common to all stylesheets, this barcode generator allows to turn checksum digit generation on and off.