Hi Jon,
this is from the gvim :help mapleader
" *<Leader>* *mapleader*
To define a mapping which uses the "mapleader" variable, the special string
"<Leader>" can be used. It is replaced with the string value of "mapleader".
If "mapleader" is not set or empty, a backslash is used instead. Example: >
:map <Leader>A oanother line<Esc>
Works like: >
:map \A oanother line<Esc>
But after: >
:let mapleader = ","
It works like: >
:map ,A oanother line<Esc>
Note that the value of "mapleader" is used at the moment the mapping is
defined. Changing "mapleader" after that has no effect for already defined
mappings."
what this allows me to do is set maps that say things like
map <leader>. :noh<Enter>
so that ",." will invoke :noh
but it sounds like that probably wouldn't work until multiple key chord mappings were supported