The Maven SCM plugin allows you to perform some common SCM actions.
This command is usually performed without a project, as that is what you are
checking out, so you need to specify the
SCM URL. The URL takes the same format
<repository><connection> element in your
maven scm:checkout -Dmaven.scm.url=scm:svn:http://svn.apache.org/repos/asf/maven/maven-1/core/trunk
This command is always performed on an existing project. It is used to update to the latest code from the server for the project.