Thanks Christian & Paul, much appreciated but I have already mentioned that I don’t want to use graphic elements. The font itself will create the barcode from the encoded text.
I’ve had some success in this area. The reason why the encoded text wasn’t working in InDesign was because “use typographers quotes” was selected in the preferences. Therefore, when I pasted the encoded text, InDesign converted the standard straight quotes to “curly” quotes.
Now that this has been resolved, I can move forward :).
To test this, I used an online encoder : https://www.bcgen.com/fontencoder/
This encoded the test number: 95141111020209 to: .++"")q
I then copied the text into InDesign and applied the Code 128 font: https://www.dafont.com/code-128.font
For independent verification I used this online barcode generator: https://barcode.tec-it.com/en/Code128?data=95141113020207 and using the original number, created and downloaded the barcode.
Finally, I compared the results:
The red barcode is the font version and the black one is from the online generator. As far as I’m concerned, within tolerances, this is an exact match
So now for the hard part. ie. COMPUTING THE CHECKSUM from the explanation in this link: http://www.barcodeisland.com/code128.phtml
What isn’t clear is it says: Take the value of the start character (103, 104, or 105) and make that the starting value of the running checksum. The example uses 103. I think Code 128 has 3 different flavours: A (auto) and B and C, so perhaps that’s what is referred to.
The “weighting” reminds me of MSB and LSB in binary. I have to set a few hours aside and carefully look at this and then start to construct some code to do the conversion. Bit difficult at the moment.
[EDIT] This might sound a bit rude, but if someone has another way of generating the sample barcode and checking it, that would be very helpful. I’d rather rely on this forum than unknowns on the web. Cheers.