How to set inoremap/nnoremap to "command key" on Vim?

Question

I would like to assign operation to a command key in Vim. Aren't any methods?

Answer 1

Supposing you are on a Mac, you can't map the command key in vim when it runs in a terminal emulator, only in the MacVim GUI.

If you are using the MacVim GUI, your mappings should use <D-…> as in nnoremap <D-l> <C-w>l. But it's not a very good idea for many reasons among them those listed in this other answer of mine.

Use <leader>, as in nnoremap <leader>l <C-w>l, instead.

See :help leader and :help key-notation.