ITF 14 is the barcode on cartons and outer cases: a 14-digit Interleaved 2 of 5 that carries the case's GTIN-14. It's made to be printed straight onto corrugated board, and the thick frame it usually comes in keeps it readable there.

With a bearer frame

With horizontal bearer bars

What it holds
Characters	Digits only.
Length	13 digits, or 14 with the check digit.
Check digit	Always there. Type it or leave it out: Labeljoy works it out, and if you typed one it checks that it's right.
Readable text	The 14 digits, under or over the bars.

Settings
Check digit	Barcode only leaves the check digit out of the readable text. No check digit and Barcode and text print all 14 digits.
Bearer bars	Frame - the box all round that GS1 asks for on cartons - is set as soon as you choose ITF 14. Horizontal bars keeps only the bars along the top and bottom, and No bearer bars removes them. With bearer bars the quiet zone is always kept inside them, so the Quiet zone switch goes away.

The rest of the settings - text position, color - are in the Barcode section.

What goes wrong
Invalid check digit.	The 14th digit you typed isn't the right check digit for the other 13 - often a sign of a mistyped number.
Input data needs 13 digits, or 14 with the check digit.	Too few digits.
Input data too long.	More than 14 digits.
Numeric only data expected.	The value has something other than digits.