The WAS configuration tree is composed of elements.
Some elements are very simple. Others are complex. Each element is some kind of WAS configuration type.
You can discover all the available configuration types for your WAS installation.
The exact number of types will vary by WAS version.
It will also vary according to what additional WAS products you have licensed from IBM.
In WAS version 7, there are at least 793. In version 8, there are at least 855.