I have a DNN 7 site. For new pages that are created in the portals, we want "All Users" to be checked under View Page - by default.

How do we do this? I think I've found the right template file?

/Portals/_default/Templates/Default.page.template

But I can't find any documentation about the tags therein.

It does have:

<inheritviewpermissions>true</inheritviewpermissions>

But where are the view permissions inherited from? And how to override them?

Again, we want it so that new pages are viewable to all users by default; no need to go change anything after new page creation. (Yeah, I know, but that's the requirement.)

Greg,
Create a new page and set the permissions. Export the page as a template and use that template as the basis of new pages. I believe the page template drop-down is alphabetical, so you should be able to force it as the default.

I just tested with a template, and that worked. However, when you first create the page, it only uses the default permissions (so, it doesn't indicate that it will be visible to All Users until you create the page).