Locales documentation - custom locale

[Dominik Grafenhofer]

Hi all,

I would like to create a new custom locale (basically irish english +
monday as first day of the week). Where can I find recent information
on how locales are implemented in Fedora (I am on Fedora 29)? I found
lots of outdated information, which was somewhat helpful, but also
quite confusing.

Thank you,
Dominik

Background: Gnome-shell does not allow to customize locale settings
beyond choosing one locale setting globally (ui language, currency,
first day of week,...).