Why doesn't the 'en' go into the 'default_language'?

I created a page with the content of ‘How can I enable translations that can't be translated into Korean?’, but the value ‘en’ is not entered in ‘xwd_default_language’ in the ‘xwikidoc’ table.

I thought the ‘defaultlanguage’ box disappeared from the screen, so I thought it was automatically entered, but it wasn’t. I can type it in DB, but is there any way I can do it on the screen?