dayNamesShort:["So","Mo","Di","Mi","Do","Fr","Sa"] => 2 letter days

I have looked up and down but I don't know how to change in the overview module to spell the days of the week with just two letters on this site: http://www.vhs-lengerich.de/joomla

I know it must be hidden somewhere in the #datepicker with daynamesmin, but I cannot seem to find either the datepicker (is it part of the full开发者_运维百科calendar.min.js?) or part of a module where this can be configured.

Where is the correct place to configure two letter day names, as they are used in German?

Assuming the site is using jQuery UI Datepicker indeed, you could just set the days after initializing the datepicker like this:

$("#datepicker").datepicker("option", "dayNamesMin", ['So','Mo','Di','Mi','Do','Fr','Sa'] );