Maury Markowitz wrote:
The only
situation I can think of where it's not appropriate to have a
space _after_ the ref is when there's a string of multiple references
grouped together. What situations are you thinking of?
When the next character is a period or comma.
Most style guides of which I'm aware say that superscripts should be
placed after a period or comma, not before it. That looks better to me
as well.
Apparently based on the Chicago Manual of Style.
I see now that there's one other situation where there's no space after
the </ref> tag; when it has a dash following it. I expect that's a
fairly rare occurrence.