Why request.getContextPath() wouldn't work?

[N G]

Hi,
 I asked a similar question yesterday, but I think I was misundertood as to
what I was asking...
 Here is what I would like to know...
 If you use the following code in your JSP to avoid having to hard code the
app name:
 <base href="<%= request.getContextPath() %>" />
 Is there a case where this wouldn't work?
 Thanks,
NG