– Help on schema microdata, multiple lists of items

I have a page that lists several items and each item has its own set of sub-items that are linked from there to their own separate pages. It looks like something like this:

Title: Songs Written by Person
Short summary
Subtitle: Pop songs
- List of pop songs, with links to each
Subtitle: Rock Songs
- List of rock songs, with links for each

I just learned about Schema's existence and I do not understand it. I understand that I should probably use CollectionPage here, and I thought to mark each subtitle as ItemList.

The problem is that apparently, several ItemLists are not allowed, and each ItemListElement must have a defined position – which, in my case, is not the case.

What would be a good way to tag a list of pages?