JSPX format is the XML version of JSP text format. The differences between each syntax are explained here: http://java.sun.com/products/jsp/syntax/2.0/card20.pdf. JSPX format is not supported by CAST, but here is a workaround that could manage most cases:
To manage JSPX files automatically from the J2EE analyzer, you can try to use text replacement in the JEE Analysis Unit > Analysis > Text Replacements or in the Application > Analysis > Text Replacements to remove the root tags and some specific tags with the following configuration (the goal is to transform JSPX syntax into JSP syntax):
|Regular Expression||Type||Replacing text|
|<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2"||Perl|
|xmlns:([^=]*)=\"([^\"]*)\"||Perl||<%@ taglib uri="\2" prefix="\1" %>|
If this doesn't work, you must create JSP files from JSPX files using a XSLT transformation before analyzing them.