Encoding Modes

EXC (Extended Alphanumeric Compaction mode) - allows encoding of all printable ASCII characters into about 2 characters per codeword. Within the EXC mode there are several submodes:

EXC Alpha - starts in upper case
EXC Lower - starts in lower case
EXC Mixed - numeric and other punctuation
EXC Punctuation - punctuation & bracket characters.

Binary/ASCII Plus mode - allows encoding of 256 international characters including the full ASCII set plus any 8-bit value in the range 0 - 255. This mode allows encoding approximately 1.2 bytes per codeword and so is considerable less efficient than EXC mode.

Numeric mode - allows encoding of a string of digits with a density of approximately 2.95 digits per codeword. Recommended where more than 13 digits are to be encoded. Numeric mode symbols may not contain non-numeric characters.

The maximum capacity of PDF417 symbols is approximately as follows:

Numeric mode – maximum capacity 2700 digits*
Alphanumeric text – maximum capacity 1800 characters*
Byte values – maximum capacity 1100 bytes

*Note that capital letters, punctuation, mode shifts and new lines/paragraphs reduce these value.

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