@bronze you’re right, it doesn’t work in that way 
@zwbetz if I understand right, the index wants to have a config file in /data/something/.
I’ve doing some test and researches, let me try to reformulate.
I want to make a site where there’s a navigation menu which is contextual per section. As I want this to be fully configuration, I’m looking to make it work using the front matter, rather than coding something static in the template.
Really, the navigation menu should just display pages available in the section itself. A workaround approach, (which I’ve tried but I am sure can work) is described here: SOLVED: List pages in sub-section
The drawback of this approach is that pages will be listed alphabetically (cause I reckon there’s no way to force an order) and it will display all pages.
The menu template doesn’t allow any .Section parameter so my need to ‘compose’ the call with a variable (.Section).