User blog comment:Ubersketch/Help with going into advanced googology?/@comment-11227630-20181101121343

To understand the use of ordinals, read Goodstein sequence and try to estimate some values of it.

To understand OCFs, read blog posts by Deedlit11 (1 2 3 4 5 6) and my pages (1 2). They might not use too many things on Cantor's Attic.

A "more complex definition" is my array notation (only parts up to DAN work).

Another "more complex definition" is Taranovsky's ordinal notation. Its definition is strange, but it is not very complex, especially compared with OCFs defined by Jan-Carl Stegert and further OCFs. I also wrote some explanation.

If you have questions while reading them, "talk" or "comment" under those pages.