WebSphere Commerce uses an XML directory to configure many different aspects of its behavior. Many different customization tasks will require you to modify the XML, template definition, template definition DTD, and DTD files in these directories.

By default, the XML files are stored in the following directory:

After modifying the XML files, the changes are propagated to the EAR file. Each WebSphere Commerce instance has its own enterprise archive with its own XML configuration directory. This is not necessary in the development environment. This directory is in the following location:

To this directory, the files are not directly modified or copied. The correct way to update files in these directories is to use the WebSphere Application Server Administration Console or the WAS wsadmin scripting. See the Ways to update application files topic in the WAS Information Center for additional information.

For example, if you want to add or update a messaging DTD in the enterprise archive on your WebSphere Commerce server, the intended target would be WC_eardir/xml/messaging/mymessage.dtd.
Inbound message template definition files
Message classification
Create an inbound XML message
Add messages to the Listener for WebSphere MQ