Adobe ACROBAT READER 7.0 Manual page 81

About typing in forms with barcodes
PDF forms can contain barcode form fields that the creator of the PDF document added
for various identification purposes, such as for an inventory of products. Barcode fields
are either static or interactive. Interactive barcode fields that are created in Adobe
Designer automatically encode the data that's entered into the form fields. The process of
filling in an interactive PDF form that contains a static or interactive barcode is no
different from filling in any other interactive PDF form.
Static barcode (left) and interactive barcode (right) created in Adobe Designer