Creating an effective paper forms barcode means designing a barcode so that information is encoded into it in a useful way that can be easily decoded into understandable information. Here are some things to keep in mind when designing a usable, decodable barcode.
Design a barcode that is appropriate for its intended use.
Think about how the users will submit the form to you or your processing organization. Make sure the barcode is designed to survive the printing, mailing in, faxing, and scanning processes.
Use Collections in paper forms barcodes instead of applying the barcode to the entire form. Collections ensure that you include the relevant fields in the barcode.
The Paper forms barcode collection name must be different from the object collection name
Make sure that the paper forms barcode name is different from the object name. Otherwise, the paper forms barcode will not update at the run time.
Paper forms barcodes in subforms with default names may cause unexpected results
When you include a paper forms barcodes in multiple unnamed subforms, you may get unexpected results. Rename the subforms instead of using the default name.
Consider the placement of the barcode on the form design.
You can place a paper forms barcode anywhere on the form design. Always place the barcode where it can be seen and scanned easily. Keep barcodes at least a half-inch from the edge of the paper to ensure that they are included when the form is printed.
Size a barcode for the amount of data to be captured.
There is a limit to the amount of data that can be encoded into a paper forms barcode. The size of the barcode also affects the amount of data that it can encode. If the barcode is too small to hold the user-supplied data, a red marker appears on the upper-right corner of the barcode, with a message informing you that the data set to be encoded is too large for the barcode to contain. You should perform one of these steps:
Reduce the data set by changing the default data size for some form objects, such as text fields. For example, the default limit length of each text field is 255. However, if a text field will only contain a first name, last name, or even a full name, the limit could be reduced to 20 or 50 characters, potentially solving the barcode size issue.
Using extended characters and both uppercase and lowercase letters increases the size of the data. Write a script to restrict data to alphanumeric characters and uppercase letters.
Delimiter must not be part of textual content
When you choose the delimited format for a paper forms barcode, make sure that the delimiter is not a part of your form’s textual contents. For instance, if you choose Tab as the delimiter, the contents of the form fields you are encoding cannot contain tabs because it will confuse the decoder. To avoid this confusion and to ensure that the encoder will work correctly, if the character originally chosen to be the delimiter becomes a part of the contents, you can choose a different character (such as a pipe or a comma) as the delimiter instead.
Do not embed data for image fields.
Paper forms barcodes cannot hold enough data to embed data for images. If you have an image field object on the form, either do not select the Embed Image Data option for the image field object or exclude the object from the barcode data. If the image field is included in the barcode data, the barcode displays a warning that the data length cannot be calculated.
Do not rotate Paper Forms barcodes.
Rotating a paper forms barcode will cause it to become clipped when the form is filled in Acrobat and Adobe Reader versions less than 8.0.
Test the form before distributing its
It is critical that you test your completed form in Adobe Reader as well as in Acrobat. Most users of these types of forms will only have Adobe Reader installed.
Ensure that users fill the form electronically
Make it clear to your users that they must fill the form electronically. If they print the form and then fill it, the paper forms barcode cannot encode any of the user-supplied data.
Test the maximum capacity of the paper forms barcode
You must test your forms in both Adobe Reader and in Acrobat to ensure that the capacity of each barcode is large enough to capture all of the required data. This can be done by filling each field with realistic entries of maximum length and ensuring that the barcode does not turn gray. You need to use Adobe Reader to test documents that have LiveCycle Reader Extensions ES barcode usage rights applied to them.
See also 

Design tips for using a paper forms barcode