The PDF417 is a 2D barcode. It is based on stacked barcodes. The characters are coded
in code words.
A code word consists of 17 modules, which consist respectively
of 4 strokes and 4 spaces.
The PDF417 is a very compact and flexible code with variable length. Up to 1108 bytes can be coded.
Error Correction Level:
PDF417 uses a differently strong error correction. It is used according to the code length.
By use of less than 41 code words the Error Correction level 2 is used. From 41 to 160 code words ECL3
is used. From 161 to 320 code words ECL4 is used. From 321 code words ECL5 is used.