Printronix ThermaLine Series - Manual (Page 231)

5–93 Bar Codes
Quiet Zone
Both ends of the bar code structure require blank quiet zones. The quiet
zones must be at least 0.25 inches wide and completely blank to ensure
accurate reading of the start/stop codes and to prevent adjacent bar codes
from overlapping. Be sure to provide sufficient space on the form for the
quiet zones.
Start/Stop Codes
The start/stop codes identify the leading and trailing end of the bar code.
Data Field
PDF417 provides twelve modes to encode data. The first three are
pre–established (the remaining nine are user modes, which can be defined
by users or industry associations according to specific applications):
1. Extended Alphanumeric Compaction mode (EXC). Comprised of four
sub–modes, this mode offers encodation of all printable ASCII
characters. This is the default mode; the PGL uses shift or latch
characters to enable other modes.
2. Binary/ASCII Plus mode. This offers encodation for all ASCII
characters, printable or not, and binary values.
3. Numeric Compaction mode. This offers encodation for numeric values
to a density of almost 3 digits per code word.
The PGL will automatically switch between modes to provide the smallest
encodation for the data.
Security Level
PDF417 can detect and correct errors. Each label has 2 code words of error
detection. You can select the error correction capacity based on application
needs. Specify a security level in the range of 0 – 8, at the time of printing.
PDF417 can also recover from omissions and misdecodes of code words.
Since it requires two code words to recover from a misdecode, one to detect
the error and one to correct for it, a given security level can support half the
number of misdecodes that it can of undecoded words.
PDF Print Data Field is not offered due to the large amount of data that can be
encoded.