Search notes:

Vim ex command: filetype

filetype on

filetype on
filetype on does basically a runtime filetype.vim (thus, it runs $VIMRUNTIME/filetype.vim.
When vim is running with a GUI, it also source VIM: runtime/menu.vim

filetype indent on

:filetype indent on seems to indirectly set indentexpr.

See also

The ftplugin/ runtime directory.
Ex commands

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