Code 2 of 5 is a family of barcodes that hold digits only. The best known is Interleaved 2 of 5 - ITF, or I 2/5 - which packs digits in pairs and is printed on cartons and in warehouses. The others are older or belong to one industry.

Interleaved 2 of 5

With horizontal bearer bars

What it holds
Characters	Digits only.
Length	Up to 89 digits in Interleaved, 80 in Data Logic and Matrix, 45 in Industrial and IATA.
Check digit	Optional: a Mod 10 digit at the end, which you turn on with Check digit.
Readable text	The digits, under or over the bars.

Modes
Interleaved	The compact one, and the most used. It needs an even number of digits, so Labeljoy puts a 0 in front of an odd number - check digit included - and prints it too. A 14-digit Interleaved code for cartons has a page of its own: ITF 14.
Industrial	Also called Standard 2 of 5. Simple and wide.
Data Logic	A variant of Matrix, from the company Datalogic.
IATA	The airlines' version, for baggage and cargo.
Matrix	A denser variant, used in warehouses and photo labs.

Check digit. Barcode and text adds the check digit to the bars and prints it; Barcode only adds it to the bars alone.

Bearer bars. Thick bars along the top and bottom (Horizontal bars) or all round (Frame). They spread the pressure of the printing plate on corrugated board and stop a scanner from reading only part of the code. 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
Numeric only data expected.	The value has something other than digits.
Input data too long.	More digits than the mode holds.