Well, we really need a Stata Corp input on this one.
Loosely, the more strain you put on the parser,
the greater the risk that Stata will misunderstand,
but that's just rephrasing my earlier comment
without adding any substance.
Stata sometimes to behave as if braces were another
kind of end-of-line delimiter, but not always.
Also, although the above works fine, I think you'll
see, if you look at documentation, that it is not encouraged
anywhere, even by example.
A possible counterexample to Nick's proposition can be found in the Stata 7
hardcopy manuals under -[P] if- (Page 121 of the Programming manual). This
contains an in-line phrase