Yes, there are two approaches. We can include other struts.xml file from a bootstrap, or we can package a struts.xml files in a JAR. Or both.

By Include

A typical struts.xml files will have one or more include elements:

<struts>
    <include file="struts-default.xml"/>
    <include file="config-browser.xml"/>
    <package name="default" extends="struts-default">
....
    </package>
    <include file="other.xml"/>
</struts>

The first include element tells the framework to load the struts-default.xml, which it will find in the struts2.jar file. The struts-default.xml file defines the "standard" interceptor and result definitions.

You can put your own <include> elements in your struts.xml interchangeably with <package> elements. The configuration objects will be loaded in the order of appearance. The framework reads the configuration from top to bottom and adds objects as they are referenced.

By JAR

A "module" can be added to an application by placing a struts.xml and related classes into a JAR on the classpath. FreeMarker and Velocity templates can also be provided by JAR, making it possible to distribution a module in a single, self-contained JAR that is automatically configured on startup.