mesh to mesh with sockets

[Apollo006]

Hi,

is there anyone who has already done something with sockets (attaching a mesh to a mesh). I've found an explanation but can't figure out what to do:
http://www.crystalspace3d.org/docs/online/manual/cs_7.7.6.php

It says that you have to add the following line behind the mesh tags:

<socket name="..." mesh="i" submesh="j" tri="k"/>

I have 2 cal3d files now. How do i link them to each other?

Thanks.