Splitting Call Numbers with the following RegEx - Rule and Call Number does not work with following RegEx Rule: s/(\s)([A-Z])/\n\n$2/g Call Number: 658.4 Lan A space after a capital letter will be replaced with two breaks. The testing option in the Classification splitting rules works fine. The Call Number becomes 658. 4 Lan Exporting an item / call number in the batch with label creator module, and a classification source that has RegEx as a Splitting Rule, one break will be deleted in the exported pdf. It seems it doesn't matter if the used Classification is DDC or generic / z.
A working solution was found: putting a blank after the \n Sorry