From: Harald Oehlmann on
On 31 Jul., 22:31, Keith <kilowattra...(a)use-reply-to.invalid> wrote:
> [list exec "explorer.exe /root,$qpl(data)"]
>
> couldn't execute "explorer.exe \root,L:\bc246t\data": no such file or
> directory
> "exec {explorer.exe /root,L:/bc246t/data} &"

On the wiki there is a page dedicated on exe quoting issues.
If you have time to dig through the big quantity of information, you
might enjoy:

http://wiki.tcl.tk/16336

Regards,
Harald