As it is, you have to define the comps file classes _before_ you use them.

The algorithm should be expanded so that you could also define them later
in the file.

The reason: the order classes are defined in comps file defines the order
they're shown in the installer.  If the algorithm were to be reworked you
could do something like:

----
1 base {
...
}

1 Our Server {
 @ Development
 @ ...
 ...
}

...

0 Development {
...
}
----

Now, you have to define the classes you want in 'Our Server' one by one (if
you want it to be the first entry in the installer).