Mapping Leader to a Ctrl combination not working/being ignored in NeoVim mappings?

Question

I'm trying to map my leader to <C-s> and local leader to <C-q>, in my NeoVim (0.5.0) init.lua file. I know Ctrl-S and Ctrl-Q are software flow control, and I mainly use the terminal version of nvim (but I'm happy to disable software flow control in the terminal emulator), but strangely this mapping doesn't work in graphical nvim-qt either?

This indirect mapping does work for as a leader:

vim.api.nvim_set_keymap(  ''  ,  '<C-s>'  ,  '<Leader>'  ,  {noremap = false}  )

But directly trying to set it, does not:

vim.g.mapleader = "<C-s>"

I've tried many variations such as \<C-s> and <C-S> but none seem to work when called via the vim.g.mapleader function. That said, if I do an echo mapleader it does show <C-s>, but none of the actual bindings work, they only work if I have set the leader indirectly...

If I use something conventional like these, then the mappings work...

vim.g.mapleader = " "
vim.g.mapleader = ","
vim.g.mapleader = "\\"

Any idea what is so special about trying to use mapleader with a Ctrl+Key combination?

Answer 1

Nevermind, after about a half hour playing around, I remembered the whole "prefix with <C-v> to enter 'special' characters" thing.

So, this works:

vim.g.mapleader = "^S"

But you don't enter that as literal text, instead you must literally type it as:

vim.g.mapleader = <C-V><C-S>