All of this is described in:

As I understand it, both 'implicit' and 'explicit' LSF is allowed.  Care should be taken to the STAT functions as well, so it's not trivial to make this change. It gives more readable code, so I'll have a look. (I won't be angry if someone provides patches .....)

Anyway, such a change should be tested very well on various platforms. So I think it's wise to to that for Tcl 9, not 8.x, because it might easily break some platform if not done well.