Help me configure my template variable

Hi !
I have a template variable, which value can be 1 or 0.

the pages that use this template are organized this way :

i have several root level pages :

/1.html
/2.html
/3.html

and some root level folders, each one containing several pages

/1/page.html
/1/page.html
/2/page.html
/2/page.html

i would like the default value of this template variable to be 1 only if
_ it is not a folderpage, and it is not a root level page

how can i do this ?? i already use phx, but can it test multiple variables ?? in the documentation it can make multiple tests on one variable, but can it do tests on multiple variables ? if yes what is the syntax ?
( i thought about nesting 2 phx, but that would really be unreadable ... )

thanks in advance