create content menu and theme_node_add_list() function

the theme_node_add_list() function takes $content as it's argument. Where is this 'content' coming from?

I have a website that I need to have basically two separate 'create content' (which will be named differently, of course) menus, each showing a custom set of content types that can be added. I do not want all my addable content types to be lumped onto node/add.

Originally I thought I would simply create two page types and manually list which types I needed on their respective pages. This worked ok, but I don't want to have to manually update several sections of the site each time I add or alter content types.

It was then, however, that I realized that when I removed a child content type menu item from the parent "Create Content" that they would not show up on node/add.

So, it appears that theme_node_add_list() takes a menu item as its argument? If that's true, how do I access the Create Content menu child array so I can filter out what I need. Also, how do I get the function to work on my custom pages? I've searched for the function in the entire set of site files, and I don't understand how it's called.

I realize that function is in the node module, but I felt it was more relevant here since it was dealing with menus.

Thanks in advance for your thoughts,

Blue