To recreate: 1. Ensure a label template and layout has been created for barcodes. 2. Go to label creator and select new barcode range. 3. Enter this range: From: THLS12345 To: THLS12355 An error appears next to the To: field "Must be greater or equal to the from value. Try again with this range: From: 12345 To: 12355 And there is no error. Koha should recognize the incrementation in the first example. If Koha allows for barcodes with a mix of characters per Code39, it should be possible to print a range like this.
Perhaps one way to deal with this is to add a box for a prefix. In the example above, THLS functions as more of a prefix than an incrementing character.