I know that you can refer to script-local functions using <SID> but what about script-local variables? I tried the following, and hitting <c-space> fails:
let s:testVar = "foo"
function! s:GetTestVar()
return s:testVar
endfunction
nnoremap <space> :echo <SID>GetTestVar()<cr>
nnoremap <c-space> :echo <SID>testVar<cr>
You can get around this by writing accessor functions (as above) but sometimes it would be nice to be able to refer directly.