The Check-in Client is a tool used to replicate the resources tree in the Governance Registry into your file-system or to a dump file. Much like a version control system like Subversion, you can do checkout, check-in and update operations using this tool.
You can use the check-in client tool only for registry/repository use cases. Therefore, you cannot use it for governance scenarios.
When you are checking out, you can specify which path of the collection tree should checkout and where in the local file-system checkout to. And you can give more options to make it more flexible as described in the following sections.