From: Saašha Metsärantala
> I would suggest to add a space after the first temporal expression to
> make it clear that the slash between the two temporal expressions is
> not part of the first temporal expression.

Good point, the syntax is ambiguous with the slashes since there can be any number of slashes in a URI, but I don't think a space is a good solution.   

I have changed this so that temporals (in an interval, only) are enclosed in parentheses.  

But that's not a good solution either, because other sorts of approximate, etc. expressions can begin with open parentheses.  

So, I think that the temporals within an interval need to be enclosed, but I'm not sure what character should enclose them.   I think quote may be the best solution.