Many people (myself included) have set wildcharm=<C-Z>
as suggested by :help 'wildcharm'
in their config. However in mappings I often see this is repeated
explicitly, e.g.
nnoremap <key> :buffer<Space><C-Z><S-Tab>
I prefer to refer to the setting itself, avoiding repetition and also making things more portable. A conversion of the above would be as follows.
nnoremap <key> :buffer<Space><C-R>=nr2char(&wildcharm)<CR><S-Tab>
Note the value of wildcharm
is stored as a number, so whilst it may have been
set using Vim's key code notation we'll need to convert it back to a character
to use it.