This is a JSP compiler issue. Both Tomcat and Jetty use the same JSP compiler, Jasper from the Jakarta Apache group. That is why you have the same issue with both implementations.
The construct you provide creates a problem for the compiler as it needs to recursively interpret the expressions within tags. This can make things much more complicated for the compiler. I'm not sure that the spec allows tags to have expressions substitued for values. I suspect that since Tomcat and the underlying Jasper compiler is the Sun reference implementation, that this is not the case. Oracle may have made their own interpretation and included this enhancement.
Please note that JBoss incorporates many other technologies and these components and their operation are not governed by the group, nor may the questions be adequately covered in these forums. You may need to raise this with the Tomcat group if you feel that the compiler does not meet the JSP 1.2 spec.
Hope that helps.
ok thanx..That would make sense.
I'm going to read the specs of 1.2 on this issue.
following the specs this is a bug in the jakarta project..