Finding out custom objects, custom reports and custom alerts

Hello All,

I am working on an upgrade project. Part of a preliminary process involves listing out custom objects, custom reports as well as custom alerts. I have ran the below query.

Select * from all_objects where where object_name like 'XX%'; because we generally name the custom object in such a way that the initial 2 letters are XX.

But what if someone has created a custom table and he/she has not followed the above mentioned naming convention?

So is there any other way to find out which objects from the table all_objects are custom objects?

Thanks