Code 128 is a very effective, high-density symbology which permits the encoding of alphanumeric data. The symbology includes a checksum digit for verification, and the bar code may also be verified character-by-character verifying the parity of each data byte. This symbology has been widely implemented in many applications where a relatively large amount of data must be encoded in a relatively small amount of space. It's specific structure also allows numeric data to be encoded at, effectively, double-density.
Code 128 Code Sets
-
Code Set A (or Chars Set A) includes all of the standard upper case U.S.
alphanumeric keyboard characters and punctuation characters together with the
control characters, (i.e. characters with ASCII values from 0 to 95 inclusive),
and seven special characters.
-
Code Set B (or Chars Set B) includes all of the standard upper case
alphanumeric keyboard characters and punctuation characters together with the
lower case alphabetic characters (i.e. characters with ASCII values from 32 to
127 inclusive), and seven special characters.
-
Code Set C (or Chars Set C) includes the set of 100 digit pairs from 00
to 99 inclusive, as well as three special characters. This allows numeric data
to be encoded as two data digits per symbol character, at effectively twice the
density of standard data.
Code 128 Special characters
The last seven characters of Code Sets A and B (character
values 96 - 102) and the last three characters of Code Set C (character values
100 - 102) are special non-data characters with no ASCII character equivalents,
which have particular significance to the bar code reading device.

Sample of a Code 128 Barcode
Code 128 Barcode for .NET, ASP.NET supports:
- all 128 characters of ASCII
- Add Reference BarcodeLib.Barcode.dll to your .NET project (ASP.NET website, Forms, any .NET project)
In your .NET class.
BarcodeLib.Barcode.Linear.Linear barcode = BarcodeLib.Barcode.Linear.Linear();
barcode.Data = "your barcode data";
// other barcode settings.
// save barcode image into your system
barcode.drawBarcode("c:/barcode.gif");
* Please set properties
UOB and
Resolution, before you set any image size related properties like barWidth, margin.