[abecedarian]

Hi guys, I'm back again. First, I want to state that I am very grateful for the generous help I am receiving on my issue. And that goes for the mobileread site as well. Today it's quite hard to find such humane help sites.

Then, to first answer the Charis SIL question: I don't really remember where I got the font. I've looked at the properties in the Windows font viewer. It says:

Font name: Charis SIL
Version: Version 4.110; 2011; Maintenance release
OpenType Layout, Digitally Signed, TrueType Outlines

Then the question about the epub version of the epub file: it's an epub3 file. So I followed the suggestion by DNSB to throw out the application/x-font-ttf declarations in the opf file and replace it with the font/ttf or the application/font-sfnt font type as an experiment. Both replaced font types were now fully accepted by EPUB-Check, so the reports came out clean this time. Then I twice replaced the epub in Calibre (with the altered opf font type declarations included) and opened the book. Unfortunately it didn't solve the problem as both times the split lines were still there.

Third, I'm running Calibre 3.48. I know it's not the latest version available, but I can't upgrade to the latest version of Calibre as long as I run my computer on Windows Vista. I'm still very hesitant to upgrade to Windows 10, as it will rob me from a very large number of adaptations I made to numerous applications which will all have to be re-installed from ground zero when I upgrade to Windows 10.

To me it seems like the only solution is to upgrade Calibre to version 5.2, as there's a chance that the issue may have been solved in that version (according to Jon).