The JAXP RI, including the JAXP bundled with J2SE 1.4 RI, uses the Apache XML project software as the implementation; namely, Xerces and Xalan. Since JAXP is now bundled with J2SE 1.4, a common question from developers is about upgrading the implementation. J2SE 1.4 provides an "Endorsed Standards Override Mechanism," which can be used to override very specific, non-core packages in the JDK itself. The new JAR files can be placed in a specific directory and passed to the JVM using a system property java.endorsed.dirs (for example, -Djava.endorsed.dirs=/usr/home/jar/).