I am asking here since it is a rather low level issue: In Plasma 5 how (and where) are the localized date and time formats defined?

For example, in Greek, the date is displayed as "12:17 Μ.Μ.", and I would like to find where the string "Μ.Μ." is defined. I think I am looking for some .po files, but the KDE source code is endless!
What I found is only how the format is defined (in /usr/share/kf5/locale/countries/gr/country.desktop), not where the actual strings are.