Captain Jack wrote:

>> (Actually, so far I've yet to find anything with a barcode other than
>> the four on the right. However, I'm told that packing cartons often use
>> a varient of I25...)
> 
> In all of the programming projects I've ever done involving printing of bar 
> codes, I've only ever used those... mostly code 39, although I used 128 once 
> for making very small bar codes, and 2 of 5 for an PO system where the 
> vendor specs required that format.

Indeed, code 39 and code 128 seem quite popular. I've found very few 
code 93 barcodes. (And, obviously, UPC-A / EAN-13 is everywhere.)

> In most cases, I've used some external tool, like a specialized bar code 
> printer, to generate the symbols. I did once (about 15 years ago) have to 
> write a program to generate code 39 on a laser printer by iterating the 
> rectangles myself. I had to copy the spacing out of a book, which was a 
> weekend well spent, let me tell you. :D

In PostScript, it's not a challenging thing to do. (As you can see, I've 
just done it.)

I'm currently writing a small Haskell library for this. Currently it 
understands 2 of 5 standard and interleaved, code 128, and I'm currently 
implementing code 39. Of course, the library only handles converting 
characters into 1s and 0s and back again. In "real" barcode handling 
things are far more complex; bar thicknesses have to be within certain 
tollerances when printing, and scanning is a fairly sophisticated problem...

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