[z3-five] Overriding main_template in zcml

[yary]

Hello,

I'd like to specify in zcml that I have a main_template in the
filesystem I'd like to use fro my CMF site. I don't know what to put
in the "for" attribute, or even if it's possible. I've created a
main_template.pt file in my product's directory, and added this to my
configure.zcml:

    <browser:page template="main_template.pt"
                  name="main_template"
                  permission="zope.Public"
                  for=" ? "
    />

What does the " ? " become, to say that I want to use my
main_template.pt for CMF sites?

I suppose I'll have to add a "traversable" tag as well, since I'm using Five 1.4

(Should I subclass CMF Site, so my new template doesn't affect other
CMF sites? Not even sure how to go about that... sorry about being a
newbie.)

Thanks in advance