mod_wsgi_app in Silva buildout

Hello devs

I want to use Silva 2.3 behind Apache using mod_wsgi.
To do this, I have to create the wsgi app silva/parts/mod_wsgi_app/wsgi.
To create this app using buildout, I had to modify the profiles/base.cfg.
In this configuration, there's a part defined as:
===
[mod_wsgi_app]
recipe = collective.recipe.modwsgi
eggs = ${wsgi:eggs}
config-file = ${deploy.ini:output}
===

However, I don't see this part called.
===
[buildout]
extends = versions.cfg
unzip = true
parts =
    zodbupdate
    instance
    cache
    wsgi
    deploy.ini
    debug.ini
===

Only after I've added mod_wsgi_app to the parts section, buildout is creating the wsgi app:
===
[buildout]
extends = versions.cfg
unzip = true
parts =
    zodbupdate
    instance
    cache
    wsgi
    deploy.ini
    debug.ini
    mod_wsgi_app
===

Is this the intended behavior?

Regards,
Benno 
______________________________________
ETH Zurich
Benno Luthiger
IT-Services
WEC E 17, Weinbergstrasse 11
8092 Zurich, Switzerland
Tel: +41 44 632 57 65
______________________________________