What is the purpose of "mx archive"?

[Jaroslav Tulach]

Hi.
All the build.xml files generated for NetBeans have:

<exec executable="/usr/bin/python2.7">
            <env key="JAVA_HOME" value="/usr/lib/jvm/java-8-oracle"/>
            <arg value="/home/jarda/NetBeansProjects/graal/mxtool/mx.py"/>
            <arg value="archive"/>
            <arg value="@GRAAL"/>
</exec>

what actually that step does? I would assume it copies the generated JAR
somewhere, but I am new to python so I feel safer to ask than to read the
code.

Thanks for your patience.
-jt