orderby field – list of available options?

I would like to sort items by the “order” field of the page attributes (see pic).

I’ve come across all kinds of “custom tag” solutions but not one listing all of the already available fields you can use with orderby. I’d like to use the “order” field as shown in the editor. I’d tried replacing the orderby field in the template with “order” but I don’t see any results.

I’m currently using:

post_type=projects&order=ASC&orderby=order&offset=1&posts_per_page=100