UCC/EAN-128^[3] encodes structured data proposed by various industry standard organizations and authorized by UCC/EAN organization. Each data type is identified with a numeric value, called Application Identifier (AI). Multiple AIs and data values can be concatenated together into one barcode, such as:

(01)19421123450011(15)991231(10)101234

The data above contains multiple AIs and values:

The AI value determines the meaning and the length of the data part. Many of them encode a predefined length of data. For example, the SCC14 requires exact 14 digits and the Sell By Date requires exact 6 digits in YYMMDD format.

When the data length can be derived from AI, it is not necessary to add field separator (FNC1) in the barcode to separate two adjacent fields. However, if the first field has a variable data length, such a field separator is required. And in many applications it is often desirable to have a field separator between two fixed-length fields. The Code128 symbol character FNC1 serves this purpose.

To understand each data field, Barcode DLL requires you to enter the data in a special format. The AI must be enclosed with parentheses. From the AI Barcode DLL knows whether a field has a fixed length or a variable length. For all variable-length fields, Barcode DLL inserts field separator unless it ends the input.

Barcode DLL also performs data validation on the AI and the data, if the AI is known to the program.

If the AI is not listed in the table above ^[5], Barcode DLL can not know whether its data length is fixed or variable. Thus, Barcode DLL treats the data as if its data length is variable and insert the field separator FNC1 when this field does not end the symbol.

For example, suppose that you set Message to (01) 19421123450011(8019)123456(15)051210. Barcode DLL understands that 01 AI requires fixed-length 14 digits data and AI 15 requires fixed-length 14 digits data. However, Barcode DLL does not understand AI 8019 and treats this field as if it has a variable length. Barcode DLL inserts a field separator at the end of this field (before AI 15).

Assuming that AI 99 requires a fixed data length and you'd like to reduce the overall barcode size, you can tell Barcode DLL that the field has a fixed data length by appending a tilde character ~ at the end of the field. For example, you can assign the value below:

(01)94211234500122(8019)123456~(15)051210

When Barcode DLL sees the ~, it treats the current field as fixed-length.

On the other side, if a known AI has a fixed data length but you'd like to have a field separator at the end of the field, you can do so by adding an exclamation character at the end of field, such as:

(01)94211234500122!(8019)123456(15)051210

It forces a field separator to appear after the SCC14 number even AI 01 has a fixed data length and the field separator is not required. Sometimes this field separator is desirable because it is easier for the application to parse the input.

See the table below for a comparision of results produced by different inputs. The[ GS] is the scanner output for FNC1 character.

Barcode	Data input/Scanner output
	(01)94211234500122(8019)123456~(15)051210 0194211234500122801912345615051210
	(01)94211234500122!(8019)123456(15)051210 0194211234500122[ GS]8019123456[ GS]15051210
	(01)94211234500122(8019)123456(15)051210 01942112345001228019123456[ GS]15051210

Before version 3.4, Barcode DLL calculates mod10 check digi on SCC-14 and SSCC-18 numbers, but only When the property UccEanOptionalCheckDigit is TRUE. This behavior was changed in version 3.4. Now the program calculates mod 10 check digit automatically, regardless the value of UccEanOptionalCheckDigit. This renders this property useless.

Barcode DLL performs check digit calculation on those AIs: 00, 01, 02, 410, 411, 412, 413, 414, 415, and 8018.

To create the barcode correctly you must enclose the AI with parentheses ( ). Barcode DLL only accepts numeric AI values. It reports an error when encountering a non-numeric character in the AI part. If AI does not appear in the known list (see the table above), and you do not want the data treated as variable length, you should tell so by appending a tilde character at the end of the field.

Some times, it is desirable to have the data separated by spaces in the human readable text. For example, you may like to see the human readable text (8101) 0 54321 1200(21)123456 instead of (8101)0543211200(21)123456. You can create the desirable human readable text by entering the message exactly like the one you'd like the human readable to be. Barcode DLL ignores the spaces during the encoding, but preserves them in the human readable text, as the one below illustrates:

Barcode DLL performs the following validations during the encoding process:

If your application does not pass the validation, you can not use UCC/EAN-128 to encode the data. Nevertheless, since UCC/EAN-128 encoding is based on Code128 symbology, you can encode the data directly with Code128. Here are several hints you may consider when converting the EAN-128 data into a Code128 input:

For example, Code128 with message ~18101054321120021123456 produces the exact barcode as the one using UCC/EAN-128 with message (8101)0 54321 1200(21)123456.

Some non-standard applications do not encode the FNC1 at the starting message. When this is the case, remove ~1 at the beginning of the input.