There aren't any that can be derived from the PPM database itself really.
Many of the out of the box objects and attributes do not follow the same Studio metadata rules and storage as the custom (aka user-defined) objects and attributes do.
Instead some of their metadata is found on disk (in the various %niku_home%\META-INF\%component%\omd\*.xml files where %component% is replaced by things like projmgr, resource, timeadmin, etc.).
Others may even be in unreadable places, such as system data providers (tied into the java code).