From OpenSCADAWiki
The World Calendar System
Counting the World Calendar System begins from 5508 before AD and was used on the SLOVISH-ANTIC territory before the jewi-arias occupation with that "Anno Domini" and Christianity (aria and now jewish). This Calendar System was used here in parallel up to XVIII century, so its was appended to TDE by the patches kcalendarsystem_World.patch in tdelibs-trinity and tdebase-trinity, initially in a simple form.